Doak, a former international cricketer, made his Ulster debut in 1995 against Northern Transvaal and has accumulated 75 caps for the club as well as eight appearances for Ireland A.
Despite a series of injuries which threatened his representative career it was whilst working as an Ulster Branch Development Officer in 2001 that then Ulster Coach Alan Solomons drafted him into the squad and gave him his first start in six years against Leinster.
Doak will return to a position within the IRFU Ulster Branch as a High Performance Coach with a responsibility for elite players at Academy Level 1 (16 - 19 year olds) and hopes to continue to play club rugby.
"I have been very happy with my rugby time, it has played a big part in my life and it still will for a while yet."
"I'd like to take this opportunity to thank all those players, coaches and backroom staff I've had the privilege to work with over the years, and of course the Ulster Rugby fans who have supported me throughout my career. I will remain closely involved with rugby through my job and am looking forward to giving something back to the sport."
Meanwhile second row Gary Longwell will win his 150th cap for Ulster this Friday night when he takes to the field at the Arms Park against Cardiff in the Celtic League.
Ulster Rugby's longest serving stalwart with a career spanning 14 years, Longwell made his Ulster debut in 1991 as a nineteen year old and earned many of his caps prior to the start of the professional era. A member of Ulster's European Cup winning side in 1999 he reached the 100th cap mark back in October 2001 against Wasps at Ravenhill in the Heineken Cup
Earlier this season he received an ERC Elite Award when he topped the 50 European Cap mark joining a select group of the top players from across Europe.
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