United States Senate elections, 1966

Infobox Election
election_name = United States Senate elections, 1966
country = United States
type = legislative
ongoing = no
previous_election = United States Senate elections, 1964
previous_year = 1964
next_election = United States Senate elections, 1968
next_year = 1968
seats_for_election = 35 seats in the United States Senate
election_date = November 1, 1966

leader1 = Mike Mansfield
party1 = Democratic Party (United States)
leaders_seat1 = Montana
last_election1 = 67 seats
seats1 = 64
seat_change1 = -3
popular_vote1 =
percentage1 =
swing1 =

leader2 = Everett Dirksen
party2 = Republican Party (United States)
leaders_seat2 = Illinois
last_election2 = 33 seats
seats2 = 36
seat_change2 = +3
popular_vote2 =
percentage2 =
swing2 =

map_

map_size = 300px
map_caption = legend|#f99|Republican holds

title = Majority Leader
before_election = Mike Mansfield
before_party = Democratic Party (United States)
after_election = Mike Mansfield
after_party = Democratic Party (United States)

The U.S. Senate election, 1966 was an election for the United States Senate which occurred midway through the term of President Lyndon Baines Johnson. As in many midterm elections, and with divisions over Vietnam in the Democratic base, the Republican opposition took three Democratic seats, but the balance remained overwhelmingly in favor of the Democrats, who retained a 64-36 majority.

Republicans won two open seats in Oregon and Tennessee and defeated incumbent Paul Douglas (D-IL).

In 1968, Republican Charles E. Goodell was appointed to the seat of assassinated presidential candidate Robert F. Kennedy (D-NY). This is not included in the party balances.

enate contests in 1966

A bolded state name indicates an article about that state's election.