Elections to the United States Senate were held on November 6, 2018. Thirty-three of the 100 seats were contested in regular elections, while two others were contested in special elections due to Senate vacancies in Minnesota and Mississippi. The winners were elected to six-year terms running from January 3, 2019, to January 3, 2025. Senate Democrats had 26 seats up for election (including the seats of two independents who caucus with them), while Senate Republicans had nine seats up for election.
The Republicans maintained a Senate majority following the 2018 elections, defeating Democratic incumbents in four states (Florida, Indiana, Missouri, and North Dakota). Democrats defeated a Republican incumbent in Nevada and gained an open seat in Arizona that was previously held by a Republican.