Mastalgia commonly presents to medical practitioners. The majority of patients can be managed by exclusion of cancer and reassurance. In some the severity of pain affects the quality of life and drug treatment should be considered. Since its inception 324 patients with cyclical mastalgia and 90 with non-cyclical mastalgia have received a therapeutic trial of drug treatment in the Cardiff Mastalgia Clinic. Overall 92% of those with cyclical mastalgia and 64% with non-cyclical mastalgia obtained a clinically useful response to therapy. Danazol was the most effective drug, with bromocriptine and evening primrose oil having equivalent efficacy. Many fewer adverse events were complained of by patients treated with evening primrose oil than danazol or bromocriptine.