We present a survey summarising the retrospective reports of the therapeutic effect of pyridoxine (vitamin B6) in 630 women suffering from premenstrual syndrome (PMS) who attended a PMS clinic during the period 1976-1983. The daily doses of pyridoxine hydrochloride varied from 40 to 100 mg early in the study and from 120 to 200 mg in the later period of the investigations. The response to treatment was recorded as good (no significant residual complaints) in 40 per cent or more of patients taking 100-150 mg pyridoxine daily and in 60 per cent of patients treated with 160-200 mg daily. Together with partial response (useful benefit but still some significant complaints), the positive effect of the treatment increased to 65-68 per cent and 70-88 per cent respectively. No symptoms consistent with a diagnosis of peripheral neuropathy were reported.