Seventeen patients have taken part in a double-blind, controlled, randomized, cross-over trial, completing four months, two months on each arm of the trial, in which pizotifen 0.5 mg t.d.s. has been compared with 1.5 pizotifen at night. Sixteen patients improved significantly. No significant difference was noted between patients on 0.5 mg t.d.s. compared with 1.5 mg nocte but there was a trend to suggest that initially patients may respond better to the t.d.s. dosage but then maintenance would be more easily carried out on a once nightly regime of pizotifen 1.5 mg nocte. Weight gain appeared to be related to the t.d.s. dosage regime and if this finding is confirmed in subsequent studies then the single dosage at night would certainly be preferable to a t.d.s. dosage regime. We confirm previous studies which show that pizotifen is extremely useful in the prophylaxis of migraine.