Northants have offered veteran batsman David Sales a new one-year contract.
Northants have also confirmed that Con De Lange, Sam Sweeney, Luke Evans and Christian Davis have all been released.
Sales, 35, has been at Northants for his entire career, which began at the County Ground back in 1998.
Sales has suffered some serious knee injuries in the past few years, but he was back to his consistent best this season, helping his country to promotion to Division One.
He scored 919 runs in the Championship with a healthy average of 45.95, scoring three centuries in the process.
Chief executive David Smith said: "Releasing players is always a tough decision. But players do get to an age when they need to be playing regular 1st XI cricket. We believe that Con, Sam, Christian and Luke are at this stage of their careers and had yet to claim regular first-team places.
"Northants Cricket would like to thank the players for all their effort and time and wishes them well in the future. They will always be welcome at Northants."
Northamptonshire have also started the process of recruiting a new left-arm spinner, a seamer and an overseas bowler.
A club statement read: "The players have been identified and head coach David Ripley is currently talking to those players. The club hopes to make an announcement shortly."
Trent Copeland took 45 wickets in his 10 Championship matches this season but the Australian will not be eligible to play for Northants in the top flight next summer.
To play county cricket as an overseas player, individuals must have played a Test match in the past 24 months, and Copeland's last appearance for Australia was in September 2011.
Monty Panesar has been linked with the club, and Northants have confirmed an interest in the England spinner who left Sussex under a cloud this summer following his infamous Brighton nightclub shenanigans.