- Kim Hae-sook - Jeong Ro-sa
- Jung Moon-sung - Do Jae-hak
- Kim Hye-In - Myung Eun-won
- ??? - Heo Sun-Bin
- ??? - An Chi-yong
- Moon Tae-yu - Yong Seok-Min
- Choi Young-jun - Bong Kwang-Hyeon
- ??? - Song Su-Bin
- Bae Hyeon-seong - Jang Hong-do
- Kim Kang-min - Im Chang-Min
- ??? - Choi Seong-Yeong
- Cho Yi-hyun - Jang Yoon-bok
- ??? - Jo Young-Hye
- Lee Su-mi - Auntie Wang
- ??? - Ju Jeon
- Kim Kap-soo - Ju Jong-su
- Park Han-sol - ER Nurse
- Shin Do-hyun - Bae Jun-Hee
- Yang Jo-a - Hwang Jae-Shin
- Park Ji-yeon - Yoon Shin-hye
- Seo Jin-won - Min Ki-Jun
- Jeon Kwang-jin - Jong Se-Hyuk
- Seol Yu-Jin - Eun Seon-Jin
- Kim Ji-seong - Han Seung-Ju
- Yoon Hye-ree - So Yi-Hyun
- Lee Ji-won - Han Hyun-Hee
- Kim Bi-bi - Ham Deok-Ju
- Lee Dal - Kim Jae-Hwan
- Lee Noah - Lee Young-Ha
- Hwang Bae-jin - Hwang Bae-Jin
- Lee Se-hee - Kang So-Ye
- Choi Young-woo - Cheon Myung-Tae
- Joo Bo-bi - Kim Da Young
- Choi Yun-seol - Yoon Ga Hee
- Lee Hye-eun - Guk Hae-Sung
- Jwa Chae-won - Nam Yoo Ri
- Lee Jung-won - Hwang Ji-Woo
- Nam Joong-gyu - Choi Se-Hoon
- ??? - Kim Geon
- Shin Hye-kyung - [Shin Hye's mother]
- Park Jung-In - Seo Yoon Hee
- Lee So-yoon - Kim Tae-Yeon
- Hong Seok-bin - Kwon Sun-Jeong
- Ahn So-yo - [Mother]
- ??? - [Chief neurosurgeon]
- Lee Ji-hoon - Lee Ji-hun
- Gi So-you - Seung Chae
- ??? - PD Song
- Park Seoung-tae - [Brain Cancer Patient]
- Bae Seong-il - [Electrician]
- Mi So-yun - [Nurse]
- Park Ji-yeon - [Eun Ah's mother]
- Hwang Young-hee - [Patient's relative]
- ??? - [Min Young's mother]
- ??? - [Jung Won's eldest sister]
- ??? - [Jung Won's second eldest sister]
- ??? - [Jung Won's second eldest brother]
- Song Duk-ho - [KWMC resident]
- Choi Seung-yoon - [Song Hwa's ex-boyfriend]
- Kim Kuk-hee - Gal Ba Ram
- Kim Sung-cheol - Noh Jin Hyeok
- Jeong Han-bin - Han Seung Hyeok
- Kim Han-jong - Gong Hyeong Woo ['Good Samaritan' patient]
- Lee Mi-eun - [Upset patient]
- Min Kyeong-ok - [Patient]
- Hwang Jae-yeol - [Patient's son]
- Seo Sung-Jong - [Heart patient]
- Kim Kyeol - [Neurosurgeon]
- Kim Dae-gon - [Ba Ram's husband]
- Park Ok-chul - [Patient's daughter]
- Kim Choo-wol - [Sung Hyuk's mother]
- Lee Cheon-mu - Won Jun
- Kwon Gwi-bin - Dr. Tae In
- Shin Joo-hyup - Jung Ho Jun
- Lee Chang-jik - Jung Su Beom
- Jung Yoo-min - Jung Eun Bin
- Ki Eun-se - Yuk Hye Jung [Ik Jun's ex-wife]
- Oh Dong-min - Yuk Hee Gwan [Ik Jun's patient]
- Ji Min-hyuk - Hee Dong [Chan Hyung's father]
- Lee Mi-young - [Su Bum's wife]
- Hong Ji-hee - [Hee Gwan's wife]
- Shim Dal-gi - [Chan Hyung's mother]
- Kim Nam-jin - [Chan Hyeong's grandmother]
- Ha Yi-An - Jae Hun / Jae Yong
- Jeong Joon-hwan - [Priest]
- Lee Ju-a - [Teen girl discharging blood]
- Lee Sae-byeol - [Mother in labor]
- Anupam Tripathi - [Foreign patient's co-worker]
- Yoon Geumseon-ah - [Baby Jae Won's mom]
- Yoon Geumseon-ah - Baby Jae-won's Mother
- Kim Young-hee - [Waitress]
- Choi Hyun-jun - [Heart procurement team 2]
- Heo Ji-na - [Chang Mo's mother]
- Choe Seong-min - [Marathon announcer - Special voice appearance]
- Kang Chung-hun - [Paramedic]
- Son Kyoung-won - Oh Jae Il
- Heo Soon-Mi - Kim Jae Young
- Kim Ga-hee - Bin [Jae Il's daughter]
- Jeong Dong-gyoo - Go Young Min [Ah Ra's father]
- Bae Yu-ri - [Social worker]
- Yang Seung-geol - [Tae Jin's father]
- Lee Soo-hyung - [Gun Hee's father]
- Park Hyun-jeong - [Gun Hee's mother]
- Yoon Byung-hee - [Jae Young's husband]
- ??? - [Ik Jun's ex-girlfriend]
- Kim In-kyung - [Surgical ward nurse]
- Jang Gyeok-su - [Ji A's father]
- ??? - [Ji Ah's mother]
- Son In-yong - [Pregnant wife's husband]
- Lee Ji-hyeon - Shin Mi Jin
- Kim Keum-soon - [Worried mother of patient]
- Kim Sun-young - [Ik Jun's patient / Shop owner's wife]
- ??? - [Patient's husband / 'Phoenix' shop owner]
- Hwang Ki-seok - [Heart surgery patient / Chang Mo's father]
- Kim Gyeong-min - Mr. Jung [Tae Yang's aide]
- Lee Seo-jun - Kim Hyun Su [Brain tumor patient]
- Kang Jeong-woo - Jo Moon Jung [Baby Hun's father]
- Kim Ik-tae - Choe Jung Won [Liver cancer patient]
- Jang Joo-yeon - [Pediatric Surgery Nurse]
- Kim Joo-ah - [Doctor]
- Kim Geon-ho - [Patient]
- Kwon Seung-woo - [Jae Young's husband]
- Ahn Su-bin - [Jung Won's daughter]
- ??? - Oh Yu Min
- Chae Seo-eun - Shin Mo Rin [Nursing student]
- Shin Hyeon-jong - [Yu Min's father]
- Lee Jun-hee - [Tae Hui's father]
- Song Min-ji - [Tae Hui's mother]
- Chae Yoon-hee - [Aneurysm patient's mom]
- Han Sa-myeong - Kim Hae Beom
- Sung Dong-il - Peter [Jung Won's eldest brother]
- Sung Dong-il - Dong Il / Peter
- Kim Kyeong-il - Hong Jeong Ho [Captain]
- ??? - [Interpreter]
- Kim Hieora - An Seong Ju
- Kim Hieora - An Seong
- Jang Hye-jin - Min Ha's Mother
- Park Eun-young - [Hae Beom's aunt]
- ??? - So Mi [Su Bin's daughter]
- Yoo Byung-sun - Im Jang Hun
- Kim Jung-soo - [Chang Hak's father]
- Shin Yeon-sook - [Chang Hak's mother]
- Shin Hee-cheol - [Chang Hak's brother]
- Chu Yeon-gyu - Ok Gang Nam [Doctor]
- Chu Yeon-gyu - [Doctor]
- Lim Seung-beom - [Baby Chae Yun's father]
- Kang Yeon-jung - [Baby Chae Yun's mother]
- Woo Sung-min - [Child patient in elevator]
- Kim A-ram - [Chang Hak's sister-in-law]
- Jeong Si-yul - Dong Ju
- Jeong Min-sung - Chang Hak
- ??? - [Chang Hak's wife]
- Hong Lu-hyeon - [Stillbirth mother]
- Go Do-yeon - Ji Hyun [Patient]
- Hwang Hee-jung - Han Seung Hui [Pregnant woman in waiting room]
- Song Hoon - [Patient]
- Lim Jung-min - [Attorney]
- Jeon Jun-woo - [Ji Hyun's father]
- Kim Mi-hui - [Ji Hyun's mother]
- Kwon Hyuk-soo - [Jung Min's father]
- Cha Mi-kyeong - Cha Mi Kyung
- Lee Jung-yeol - [Astrocytoma patient]
- Nam Sang-ji - [Cirrhosis patient's wife]
- Yook Mi-ra - [Cirrhosis Patient's mother]
- Jang Ha-eun - [Brain hemorrhage patient's daughter]
- Eom Ok-ran - [Astrocytoma patient's wife]
- Woo Jeong-won - Yeom Se Hee [Doctor]
- Lee Dong-hee - [Stroke patient]
- Cha Chung-hwa - [Yeon Woo's mother]
- An Si-ha - Kim Soo Jung
- Lee Taek-geun - [Soo Jung's husband]
- Na Chul - Kim U Jae [Doctor]
- Bae Ki-beom - Kim Jang Ho
- Kim Si-woo - Park Seung Won
- Jeon Hye-yeon - [Nurse]
- Ryu Hye-rin - [Seung Won's mother]
- Seo Suk-kyu - [Seung Won's father]
- Seung Eui-yeol - [Gyung Jin's father]
- Lee Ji-ha - [Gyung Jin's mother]
- Lee Eun-joo - [Eun Ji's mother]
- An Tae-rin - Ha Yul
- Son Seung-hoon - Cho Seon Ho
- Lee Kyoo-hyung - Yoo Han Yang [Gyung Jin's brother]
- Ahn Chang-hwan - Baek Hyeong Do [Doctor] [Voice]
- Ma Jeong-pil - [Doctor]
- Jeon Soo Yeon - [Patient's daughter talking to Dr. Do Jae Hak (Voice)
- Jeon Soo Yeon - [Suk Hyung's patient]
- Heo Seon-haeng - [Heart patient]
- Kim Mi-ra - [Ha Yul's mother]
- Go Han-min - [Ye Rim's husband]
- Kim So-woon - [Heart patient's wife]
- Hong Yoon-hee - [Ye Rim's mother-in-law]
- Choi Sol-hee - [Impatient heart patient]
- Yoon Sung-won - [Impatient heart patient's husband]
- Seo Gwang-jae - [Recovered cancer patient]
- Im Too-chul - [Recovered cancer patient's son]
- Yeon Si-woo - Lee Gyung Mi
- Park Tae-sung - [Min Chan's father]
- Ko In-beom - Jang Jong Gil
- Kim Kyu-baek - Jong Gil's Son
- Kim Ja-young - Jong Gil's Wife
- Oh Eun-Seo - Ba Da
- Choi Deok-moon - Chu Cheol Woo
- Choi Deok-moon - [Min Ha's father]
- Ryu Yeon-seok - [Fellow]
- Yoon Dan-bi - [Doctor]
- Kim Jin - [Ba Da's mother]
- Lee Jeong-chan - Jong Seop's Son
- Han Seo-yeon - Physical Therapist
- Lee Jae-Soon - [Seizure woman]
- Park Soo-jin - [Boy patient's mother]
- Lee Ji-hyeon - Sim Mi Jin [Min Chan's mother]
- Kim Geun-bae - [Ba Da's father]
- Ki Hwan - [Eun Ji's father]
- Im Jae-geun - [Ru Bin's father]
- Jung Seo-in - [Patient from Jinhae]
- Lee Dong-yong - [Husband from Jinhae]
- Kim Hyun - Choi Eun Suk
- Kim Hak-seon - [Eun Suk's husband]
- Joe In - Kim So Young
- Kang Hak-soo - [Patient]
- Lee Ha-joo - [Cafe cashier]
- Kwak Na-yeon - [Patient's wife]
- Ahn Sang-woo - [Ik Jun's professor]
- Goo Jae-yeon - [So Young's mother]
- ??? - [So Young's husband]
- Jeong Eun-gyeong - [Du Na's mother]
- Kim Ro-sa - Pediatrician
- Lim Han-bin - Han Jun
- Han Ki-jang - [Paramedic]
- Kim Ga-young - [Jun's mother]
- Kang Moon-kyung - [Seong Ju's father]
- Hong Woo-jin - [Seong Ju's brother]
- Kim Beom-soo - [Security guard]
- Min Ji-a - [Preterm baby's mother]
- Park Se-in - Sun Seong Hui
- Park Se-jin - Hwang Du Na
- ??? - [Song Hwa's mom] [Voice]
- ??? - [Brain tumor patient]
- ??? - [Brain tumor patient's son]
- Choi Yoo-song - [Brain tumor patient's daughter]
- Kim Jin-bok - Ko Ju Hyeong
- Yoo Jae-myung - Shin Sung Eui
- Lee Yun-sang - Doctor
- Lee Si-young - Pregnant Nurse
- Lee Bom-so-ri - OB-GYN Fellow
- Kim Ki-nam - Table Tennis Umpire
- Bae Hyun-kyung - Dr. Shin's Teammate
- ??? - Jang Young-seok
- Han Ji-hyo - Intern
- Jang Joon-ho - Doctor
- Choi Ji-yeon - Doctor
- Jeong Hyun-seok - Pediatrics Doctor
- Kim Hee-chang - Chan Dong's Friend
- Lee Do-hye - Ki Eun Mi
- Lee Tae-hyeong - An Sang Mo
- Bae Min-jun - Sang Mo's Son
- Lee Hyo-je - Sang Mo's Son
- Goo Si-yeon - Sang Mo's Wife
- Jeon Yeo-jin - Ho Jung's Sister
- Lee Young-sook - Ho Jung's Mother
- Jung Chung-gu - Bae Jong Seop
- Park Jae-Joon - Choi Eun Dam
- Jo Nam-hee - Doctor
- Jang Won-hyung - Pediatrics Fellow
- Seol Chang-hee - Seo Joo's Husband
- So Hee-jung - Bae Jong Sup's Wife
- Park Mi-sook - Seung Chae's Mother
- Choi Kyo-sik - Bae Jong Sup's Mother
- An Hui-ju - Brain Hemorrhage Patient's Daughter
- Ko Kyoung-hee - Ju Hyeong 's Wife
- Lee Il-sub - Sim Yeong-Su
- Lim Ji-ho - Jae-min
- ???
- ???
- Kim Song-hee
- Chae Jin-ah
- ???
??? interpreta a Lee Ik-jun en la serie.
Yoo Yeon-seok interpreta a Ahn Jung-won en la serie.
Jung Kyung-ho interpreta a Kim Jun-wan en la serie.
??? interpreta a Yang Seok-hyung en la serie.
Jeon Mi-do interpreta a Chae Song-hwa en la serie.
??? interpreta a Jang Gyeo-wool en la serie.
Ahn Eun-jin interpreta a Chu Min-ha en la serie.
??? hace el papel de Lee Ik-sun.
Kim Joon interpreta a Lee Woo-joo en la serie.
Kim Hae-sook interpreta a Jeong Ro-sa en la serie.
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