A low-dose danazol maintenance therapy (mean total dose 800 mg per month) was given during the luteal phase to 34 women with severe relapsing cyclical mastalgia. On conventional danazol dosage, all subjects had previously obtained a useful clinical response, but side effects occurred in 29 (85 per cent). Using this low-dose regimen, complete relief of symptoms was achieved in 15 women (44 per cent); the remainder obtained a substantial clinical improvement. Side effects were reduced to 12 per cent of women and were considered mild and tolerated by all patients. A low-dose regimen may be suitable for women with severe persistent cyclical mastalgia and minimises side effects that develop on conventional dosage.