e23285 Background: Male breast cancer (MBC) is rare. The features of MBC shares similar characteristics with female breast cancer, often resembling postmenopausal breast cancer. However, there are notable differences between male and female breast cancer, especially regarding gender and age, which can have distinct psychological impacts on male patients. In this study, we investigated whether the psychological distress experienced upon a diagnosis of breast cancer differs according to gender. Methods: Data were obtained from the National Health Insurance claims database of the Health Insurance Review and Assessment Service in South Korea. This study focused on the three most common psychological disorders: sleep disorders, anxiety disorders, and depression. Diagnosis confirmation relied on diagnostic codes based on the International Code of Disease, 10th revision, alongside breast cancer diagnoses. Propensity score matching was used in a 1:5 ratio, and adjustment variables included age, endocrine therapy, chemotherapy, HER2-targeted treatment, and Charlson Comorbidity Index score. Results: After excluding patients with previous psychological disorder, there were a total of 75,936 patients, and 281 (0.4%) male patients. Male patients were diagnosed at an older age, had a higher prevalence of hormone receptor-positive status, higher comorbidities, and lower rates of anxiety disorders, while sleep disorders and depressive disorders showed similar incidences. The Cox proportional hazard regression model exhibited that being female was a risk factor for anxiety disorder (after matching, multivariable, HR 1.498, 95% CI 1.057-2.123, p = 0.023). However, gender did not significantly influence the development of sleep or depressive disorders, despite these conditions typically having a higher incidence in females. During the acute phase shortly after diagnosis, women tend to have more distress, as seen on the cumulative incidence curves. Conclusions: MBC patients experienced similar levels of psychological distress related to sleep and depression disorders as female patients. These results suggested that both genders require an equal support system and psychological care to maintain mental well-being after a breast cancer diagnosis.