The majority of breast lesions in men are benign. Gynaecomastia is a very common condition in which hormonal changes cause male breasts to enlarge. Three radiological patterns of gynaecomastia have been described: nodular, dendritic, and diffuse glandular pattern. The main differential diagnosis is lipomastia, which is when adipose tissue deposits are found in the subcutaneous tissue. Male breast cancer is rare. The main risk factors are pathologies that cause hormonal imbalances, a history of chest irradiation, and a family history of breast cancer (particularly in families carrying a mutation of the gene BRCA2). Mammography usually shows a mass with no calcifications. Sonography is useful to investigate local disease spread, and for detecting any enlarged axillary lymph nodes. MRI is not currently indicated to investigate male breast cancer. Very often, the clinical examination alone is enough to distinguish benign lesions from malignant lesions. Imaging must not be automatically carried out, but rather it should be used when the diagnosis is clinically uncertain or when patients present risk factors for breast cancer, as well as for guiding biopsies and for assessing disease spread.