This weekend's US GP will be Gary Hartstein's penultimate race as F1's medical delegate as the FIA have not renewed his contract.
Hartstein started in Formula One in 1990 working alongside Professor Sid Watkins and when the Prof retired at the start of 2005, it was Hartstein who took over as F1's chief doctor.
Seven years later his time in F1, which included chairing the FIA Institute's Medical Training Working Group, is set to draw to a close.
"Have just been informed that president of the FIA and president of FIA medical commission have decided not to renew my F1 contract," he revealed on Twitter.
"Not sure about the 'whys' of the decision, but not down to me to know. Brazil will therefore be my 247th and last F1 grand prix."
The American added that working in F1 has been "a life-changing experience and something I'll never forget.
"[There is a] long list of stuff in my life that's been ignored or not done coz [sic] of F1. Like vacations, learning to fly, waking up at home every weekend...
"If I've brought even a small bit to this sport of what it's brought to me in personal fulfilment then it was worth it. Time to start banging away at that list..."