In a double-blind cross-over study we compared tolfenamic acid with paracetamol in out-patients with common migraine (migraine without aura). Each patient was treated during (at least) 4 attacks with one of the following alternatives: tolfenamic acid 200 mg, tolfenamic acid 400 mg, paracetamol 500 mg or paracetamol 1000 mg in a randomized sequence. The same sequence of treatments was applied to (preferably) 4 more attacks. Dosage was repeated after 2 h if the attack had not abated. Escape medication was allowed after 4 h if the treatment was inefficient. A total of 83 patients were admitted to the study, but 3 dropped out, while 10 completed less than 4 attacks. Seventy completed 4 attacks, and 58 completed all 8. The total number of attacks treated was 545. We found a significant superiority of tolfenamic acid over paracetamol with regard to effect on pain after 2 h (p less than 0.01), patients' global evaluation (p less than 0.001), and use of escape medication (p less than 0.02). The trend was the same for duration of attacks, confinement to bed during attack and nausea, but the results were not statistically significant. There was no significant difference between the smaller and the larger dose of either drug nor between the need for escape medication, although the trend favoured tolfenamic acid. Side effects were few. Tolfenamic acid is evidently valuable in treatment of migraine.