The 1956 United States Senate election in Missouri took place on November 6, 1956 in Missouri. The incumbent Democratic Senator, Thomas C. Hennings Jr., was re-elected. He defeated Republican nominee Herbert Douglas, winning 56.4% of the vote. Hennings outperformed Democratic presidential nominee Adlai Stevenson II, who won 50.1% in the presidential election in Missouri.
Democratic primary
Candidates
Thomas C. Hennings Jr., incumbent Senator since 1951
Withdrew
Tom J. Gavin, Kansas City councilman (name remained on ballot)