The 2010 United States Senate elections were held on November 2, 2010, from among the United States Senate's 100 seats. A special election was held January 19, 2010 for a mid-term vacancy in Massachusetts. Thirty-four of the November elections were for six-year terms to the Senate's Class 3, while other three were special elections to finish incomplete terms. Those 37 November elections featured 19 incumbent Democrats and 18 incumbent Republicans.
After the previous elections, the Senate was composed of 58 Democrats, 40 Republicans, and 2 independents who caucused with the Democrats.
Republicans won four seats held by retiring Democrats and Republicans defeated two incumbent Democrats, for a Republican net gain of six seats. This was the first time since the 1994 elections that Republicans successfully defended all of their own seats. This was the fourth consecutive election of Class 3 senators where Democrats failed to gain seats and the third consecutive midterm election held in a president's first term where Republicans picked up seats.