Holby City's Rosie Marcel told fans she called upon her knowledge from the BBC show to help a man she found bleeding the street.
The actress, 45, who played surgeon Jac Naylor in the programme, was in the car with her daughter when she saw the stranger covered in blood.
Taking to Instagram on Saturday with a picture of the man huddled under a blanket at the side of the road, she said: "Yesterday on my way to visit my parents in law we were driving along and saw this man walking covered in blood.
"Nobody stopped. So I did," she added, before adding she "couldn't go into detail" about the incident being investigated by police.
"He was bleeding very profusely from several large wounds on his face, head and arms," Rosie explained.
"I flagged another car down to call the police and ambulance while I got my first aid kit from the boot and started applying pressure.
"My amazing daughter sat in the car and FaceTimed with her dad as she was a little scared so that I could help him. She even gave up her blanket for him to stay warm."
Pre-empting people's reaction to her not being a trained doctor, the actress clarified: "I debated posting this as obviously there will be plenty of people who will no doubt go ‘You’re not a real doctor’ - I know I’m not.
"But I do have more medical knowledge I guess than an average person? 16 years teaches you some things."
Explaining why she helped the man, Rosie concluded: "I should have stopped. I should help. I should do what I can for someone in need. There are too many of us who turn a blind eye to pain and mistreatment. I will always stop. I’d want someone to do it for me."
The actress' positive post was met with a flurry of approval from her fans with many congratulating the star for helping the stranger.
One said: "Medical knowledge or not, what you did was incredible. You're an earth angel."
While another added: "I applaud you Rosie, I often joke that the majority of my knowledge is from watching Holby City."
Earlier this year, the actress had first-hand experience of the medical profession when she was rushed to hospital.
Sharing a picture from her ward, she told her fans: "Ended up at the old emergency room the other night. Stoke Mandeville is my new localish hospital and they were brilliant.
"Ambulance crew were amazing too. Had surgery the next day and home soon after that."
Rosie played Jac in Holby for 16 years and was devastated when the show was cancelled in March.
She told us: "I have loved playing Jac. I thought I would be playing Jac for the rest of my life actually because I loved her. Jac's my friend.
"I know she's not a real person but of course, she's me."
