The 1938 United States Senate election in Maryland was held on November 8, 1938. Incumbent Democratic U.S. Senator Millard Tydings was re-elected to a third term in office, easily defeating Republican Oscar Leser. Primary elections were held on September 12. faced a primary challenge from U.S. Representative David John Lewis, who was backed by President Franklin D. Roosevelt in the President's attempt to purge the Democratic Party of conservatives. He survived comfortably by a two-to-one margin. Leser defeated Galen L. Tait for the Republican nomination.