| Election Name: | 1942 United States Senate election in Montana |
| Country: | Montana |
| Flag Year: | 1905 |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1936 United States Senate election in Montana |
| Previous Year: | 1936 |
| Next Election: | 1948 United States Senate election in Montana |
| Next Year: | 1948 |
| Election Date: | November 3, 1942 |
| Image1: | M001108.jpg |
| Nominee1: | James E. Murray |
| Party1: | Democratic Party (United States) |
| Popular Vote1: | 83,673 |
| Percentage1: | 49.07% |
| Nominee2: | Wellington D. Rankin |
| Party2: | Republican Party (United States) |
| Popular Vote2: | 82,461 |
| Percentage2: | 48.36% |
| U.S. Senator | |
| Before Election: | James E. Murray |
| Before Party: | Democratic Party (United States) |
| After Election: | James E. Murray |
| After Party: | Democratic Party (United States) |
The 1942 United States Senate election in Montana took place on November 3, 1942. Incumbent United States Senator James E. Murray, who was first elected to the Senate in a special election in 1934 and was re-elected in 1936, ran for re-election. Following his victory in a competitive Democratic primary, Murray advanced to the general election, where he was opposed by former United States Attorney for the District of Montana Wellington D. Rankin, the Republican nominee and brother of representative Jeannette Rankin. In a closely fought election, Murray narrowly defeated Rankin to win re-election to his third term and his second full term in the Senate.