The 1968 United States Senate election in Arizona took place on November 5, 1968. Incumbent Democratic U.S. Senator Carl Hayden, 91, decided not run for reelection to an eighth term, ending his 57-year-long career in Congress. Hayden's longtime staff member Roy Elson ran as the Democratic Party nominee to replace him. Elson was defeated by a wide margin, however, by former U.S. Senator and 1964 Republican presidential nominee Barry Goldwater, who staged a political comeback. Prior to Goldwater's election, the seat had been held for decades by the Democratic Party under Carl Hayden, but after this election remained in Republican Party control continuously for 52 years, until Democrat Mark Kelly won in the 2020 special election.
Elson had previously challenged U.S. Senator Paul Fannin in 1964, when Goldwater vacated his seat in order to run for president against Lyndon B. Johnson.