Mastalgia is a common condition in women of reproductive years. We have assessed the long-term course in patients with severe mastalgia by distributing a postal questionnaire to 212 patients previously studied in 1983 who had attended the mastalgia clinic at the University Hospital of Wales, Cardiff. 175 patients (83%) responded, with an original diagnosis of cyclical mastalgia (CM) in 120 and non-cyclical mastalgia (NCM) in 55. The median age of onset of breast pain was 36 years (range 12-63 years). The average duration of pain was long (median 12 years), especially if it started in the second or third decade of life. Pain persisted in 68 (57%) of CM and 35 (64%) of NCM patients. In CM patients resolution was commonly associated with a 'hormonal' event, notably the menopause; in NCM patients it more often seemed to be spontaneous. Severe mastalgia ran a chronic relapsing course often requiring repeated drug treatments.