Essex have handed spinner Tim Phillips a new deal for the 2012 campaign, but have released young seamer Max Osborne.
Slow left-armer Phillips, 30, was the country's top wicket-taker in Twenty20 cricket last season with 26.
"Personally, I had a strong campaign in one-day cricket, especially in the Twenty20," he said.
"I will take this into 2012 to help the team improve the consistency and I'm sure we can go further in all formats of the game."
Phillips impressed in the CB40 competition too, taking 17 wickets in 12 matches, but made less of an impact in the County Championship, claiming 11 victims in eight appearances.
"Tim has had a very successful one-day season and he now needs to push on with his four-day cricket," explained his head coach Paul Grayson.
Medium-fast right-armer Osborne, 20, failed to make a first-team appearance last season, having featured twice in 2010.
He joins Chris Wright in leaving the Chelmsford club - the seamer having made a permanent switch to Warwickshire earlier in the month.