Included in the returned donations was an estimated $1,892 that was never reported for the use of Abramoff's skybox at the MCI Center in downtown Washington in 2001.
The state's other two members of Congress, Republican Sen. Conrad Burns and Republican Rep. Denny Rehberg, returned their own contributions last week. Burns returned an estimated $150,000, while Rehberg returned almost $20,000.
Abramoff, already charged with fraud in a separate Florida case, is at the center of a federal probe that has entangled at least a half dozen lawmakers and Bush administration officials. The Justice Department is investigating whether he won any undue influence through donations and favors.
Spokesman Barrett Kaiser said Baucus has never met Abramoff and never took any contributions directly from him.
"He thought it was the right thing to do on principle," Kaiser said.