Parsons has shown great loyalty to Somerset and was the oldest of the six players who were offered two-year contracts at the end of the 2004 season.
He joined the playing staff at Somerset in 1992 and enjoyed a benefit year in 2004.
He was a regular in one-day competitions in 2005, helping the Sabres win the Twenty20 Cup by hitting 215 runs and taking 10 wickets.
He also featured in eight County Championship games where he averaged 44.55 with the bat.
He has played many match-winning innings and taken vital wickets for the club, particularly in the one-day game.
His most memorable performance was his crucial unbeaten 60 against Leicestershire at Lord’s to earn the man-of-the-match award and help Somerset win the 2001 Cheltenham & Gloucester Trophy final.
A disappointing season in 2007 saw him play in all the Friends Provident Trophy matches at the start of the summer, but feature in only one further game.