Gynecomastia is a benign pathology due to the increased volume of the mammary glands. The various etiological factors lead to an imbalanced estrogen/androgen ratio or to a greater local receptivity to the former with consequent hypertrophy of the mammary stromal gland components. Although the majority of cases are benign and/or transient, gynecomastia must be carefully examined using thorough anamnesis, hormone assays and instrumental tests in order to exclude local or further removed pathology. At present, medical or surgical therapy is reserved for those cases in which this condition is painful and/or psychologically damaging. In this study, following a review of the literature, the Authors focus on the etiological, diagnostic and therapeutic aspects of gynecomastia and illustrate the cases they have observed.