Danazol is a synthetic steroid that inhibits the gonadotropin secretion. Its efficacy was tested in 27 patients with metastatic breast cancer at the dose of 200 mg three times daily. Characteristics of patients were as follows. The median age was 57 years (range, 44-85). All patients were postmenopausal, and all had previously received a median of two (range, 1-3) endocrine therapies. Estrogen receptor status was known in 12 (positive in five of 12; negative in seven of 12). Dominant sites of metastases were lung in seven, bone in ten, liver in three, and soft tissue in seven. Six of 27 patients were unevaluable for response (early death, four; lost to follow-up, two). Three of 21 patients showed an objective response, eight of 21 obtained stabilization of disease, and eight progressed. The therapy was well tolerated in the majority: gastric pain was observed in three and nausea in two. Danazol could have a role in the treatment of metastatic breast cancer as an alternative regimen when other treatment has failed.