Objective: To present management options for gynaecomastia and mastodynia associated with nonsteroidal antiandrogen therapy, supported by relevant data and case studies. Background: Gynaecomastia (male breast enlargement) and breast pain/ sensitivity (mastodynia or mastalgia) are pharmacologically expected adverse effects of nonsteroidal antiandrogen therapy for prostate cancer. They are caused by proliferation of glandular tissue in response to an increase in the ratio of estrogen to androgen. Gynaecomastia and mastodynia are benign conditions, and many patients choose to tolerate them as acceptable, usually mild or moderate, adverse effects of therapy. Recent data show that nonsteroidal antiandrogen monotherapy significantly reduces disease progression in localised and locally advanced prostate cancer, a finding that may result in wider and more long-term use of this treatment. Therefore, both clinicians and patients may benefit from increased awareness of the options available for the management of gynaecomastia and mastodynia. Management options, data and case studies: Management options for gynaecomastia and mastodynia are illustrated in a schematic flow diagram. Options identified are: (1) risk reduction using pretreatment breast irradiation; (2) stopping antiandrogen therapy; (3) acceptance of gynaecomastia and/or mastodynia in the context of the significant clinical benefit of antiandrogen treatment; (4) prompt treatment (liposuction/breast tissue excision, hormonal manipulation or pain control with irradiation or analgesics); and (5) later treatment (liposuction/breast tissue excision, hormonal manipulation or pain control with irradiation or analgesics). Where available, relevant data are discussed and the options are illustrated by case studies. Conclusions: The risk of developing gynaecomastia is lessened by prophylactic breast irradiation. Following the development of gynaecomastia, treatment options include readjustment of the estrogen-to-androgen ratio using antiestrogens, surgery in the form of liposuction or, for more advanced cases, breast tissue excision. Mastodynia may be controlled by post-treatment irradiation or analgesics.