This retrospective study investigated the incidence of breast atypia and breast cancer (BC) in patients undergoing chest masculinization surgery. Of the 880 patients included, 7 (0.8%) were diagnosed with atypia and none with BC. The median age at surgery for patients without and with atypia was 25.0 and 36.0 years, respectively. Preoperative testosterone therapy utilization was similar among patients with atypia (71%) and patients without (79%). No patients with atypia were diagnosed with subsequent BC during a median follow-up of 37 months. Appropriate BC screening and risk management for patients undergoing chest masculinization surgery should be further elucidated.