Professor Sid Watkins, who has been at the forefront of safety in Formula 1 for more than 30 years, has ended his full-time involvement in motorsport.
The neurosurgeon has stepped down as president of the FIA Institute, but will continue in an honorary role.
The 83-year-old, who was a close friend of the late Ayrton Senna, served as F1 medical delegate from 1978 until 2004.
He played a major role in saving the lives of many F1 drivers after heavy crashes.
Among them were Ferrari's Didier Pironi at the 1982 German Grand Prix, Jordan's Rubens Barrichello at Imola in 1994, and McLaren's Mika Hakkinen at Adelaide in 1995.
Senna and Watkins after Roland Ratzenberger's fatal crash at the 1994 San Marino GP
Watkins worked on improving safety in F1 alongside his full-time job at Whitechapel Hospital.
He was appointed chairman of the FIA Expert Advisory Safety Committee, which was set up in 1994 following the deaths of Austrian Roland Ratzenberger and Senna on successive days after Barrichello's crash at the 1994 San Marino Grand Prix.
Watkins recounted in his autobiography that he had tried to persuade Senna to retire in a conversation at the scene of Ratzenberger's accident, 24 hours before the Brazilian himself would crash to his death.
Senna broke down at the crash scene and cried on Watkins' shoulder.
Watkins wrote that he said to Senna: "What else do you need to do? You have been world champion three times, you are obviously the quickest driver. Give it up and let's go fishing."
Senna replied: "Sid, there are certain things over which we have no control. I cannot quit. I have to go on."
Working closely with then-FIA president Max Mosley and race director Charlie Whiting, Watkins was instrumental in transforming safety in F1 - there have been no driver deaths in the sport since Senna's on 1 May 1994.
He became the first president of the FIA Foundation for Automobile in Society in 2004.
Watkins will be replaced by Professor Gerard Saillant, himself famous for ground-breaking surgery that saved the legs of several badly injured F1 drivers, including Pironi, who died in a powerboat accident in 1987.