Atenolol, 50 mg, b.i.d., and propranolol, 80 mg b.i.d.,. were given to 28 patients with a presumed diagnosis of migraine, in a placebo-controlled double-blind cross-over study, where each period lasted 6 weeks. In the total material, atenolol was significantly better than placebo in reducing attacks, whereas propranolol showed no definite such effect. In seven patients the number of headache days was remarkably high (average: 22 headache days in 42 days), which may indicate that they have been inappropriately included in the material or have recorded interparoxysmal headache in addition to attacks. If these patients are excluded, the attack-reducing effect of propranolol and tenormin is significant and of equal magnitude.