The Cubs and Ryan Dempster agreed to a four-year contract on Tuesday.

Published reports said the new contract is worth at least $52 million. The signing secures the free agent right-hander's services through 2012.

Dempster went 17-6 with a 2.96 ERA for the Cubs last season after returning to the rotation on a full-time basis for the first time since 2002.  He finished in the top seven in the National League in wins, ERA, and strikeouts and made the All-Star team for the first time since 2000.

He set a career high and tied for third in the National League in wins, ranked fourth in the league in ERA and was third with a .227 batting average against. He also allowed only 14 home runs in 206 2/3 innings and turned in 21 quality starts, tied with Ted Lilly for most on the team.

This is a key move by the Cubs, as they return one of their best starters and keep intact their top three guys in the rotation.