1950 United States Senate election in Illinois

The 1950 United States Senate election in Illinois was held on Tuesday November 7, to elect one of Illinois's members to the United States Senate. Republican Everett Dirksen defeated incumbent Democratic Senator and Senate Majority Leader Scott W. Lucas, who had been seeking a third term.

Dirksen carried 82 of the state's 102 counties. Among the 88 counties that Dirksen won was the state's most populous county, Cook County, in which Dirksen won with 50.01% to Lucas' 49.60%. Despite losing in Cook County, Lucas performed better in the county than he did in the cumulative vote of the remaining 101 counties, where Dirksen won 57.56% to Lucas' 42.13%. 54.54% of the votes cast in the election were from Cook County.

Lucas was the second-ever Senate leader to lose re-election, and the only one to do so while his party retained the majority. Coincidently, Dirksen himself later became the Republican Senate leader in 1959. This election was the only one where both candidates became Senate Party Leaders until the 2004 United States Senate election in South Dakota.

The primaries and general election coincided with those for House and state elections.

Primaries were held on April 11.

• 1950 United States Senate elections