A 62-year-old male with a 10-year history of seropositive rheumatoid arthritis (RA) developed gynecomastia 8 months after beginning oral low-dose methotrexate (MTX) therapy. Two months after folate supplementation, the gynecomastia symptoms improved. Gynecomastia associated with low-dose MTX is a rare occurrence, with only nine cases previously reported in the literature. This is the first report showing folate supplementation to be effective against gynecomastia following low-dose MTX. Although it occurs infrequently, gynecomastia associated with low-dose MTX therapy should be considered in male patients with RA.