Background: Gynecomastia (GM) is a benign proliferation of the glandular tissue of the breast in men. It is a frequent condition with a reported prevalence of 32–65%, depending on the age and the criteria used for definition. GM of infancy and puberty are common, benign conditions resolving spontaneously in the majority of cases. GM of adulthood is more prevalent among the elderly and proper investigation may reveal an underlying pathology in 45–50% of cases.
Objectives: The aim was to provide clinical practice guidelines for the evaluation and management of GM.

Materials and methods: A literature search of articles in English for the term ‘gynecomastia’ was conducted. Evidence‐based recommendations were developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system.

Results: A set of five statements and fifteen clinical recommendations was formulated.

Conclusions: The purpose of GM assessment should be the detection of underlying pathological conditions, reversible causes (administration/abuse of aggravating substances), and the discrimination from other breast lumps, particularly breast cancer. Assessment should comprise a thorough medical history and physical examination of the breast and genitalia (including testicular ultrasound). A set of laboratory investigations may integrate the evaluation: testosterone (T), estradiol (E2), sex hormone‐binding globulin (SHBG), luteinizing hormone (LH), follicular stimulating hormone (FSH), thyroid stimulating hormone (TSH), prolactin, human chorionic gonadotropin (hCG), alpha‐fetal protein (AFP), liver and renal function tests. Breast imaging may be used whenever the clinical examination is equivocal. In suspicious lesions, core needle biopsy should be sought directly instead. Watchful waiting is recommended after treatment of underlying pathology or discontinuation of substances associated with GM. T treatment shold be offered to men with proven T deficiency. The use of selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs) and non‐aromatizable androgens is not justified in general. Surgical treatment is the therapy of choice for patients with long‐lasting GM.