Seventy patients with classical or common migraine were treated during their attacks with either naproxen sodium or placebo in a randomised, double-blind parallel group study. The initial dose of naproxen sodium was 825 mg followed one hour later by a further 550 mg, if symptoms were the same or had improved. If the migraine symptoms had worsened, patients were offered an escape analgesic combination of 1000 mg paracetamol and 10 mg metoclopramide. Patients were assessed at monthly intervals for changes in the severity and duration of headache, premonitory symptoms (mainly visual disturbances) and photophobia, nausea and vomiting associated with migraine attacks that had occurred since the previous visit. Patients were studied for a maximum of ten attacks and significant improvement was observed in the severity and duration of headache when the patients were on naproxen sodium. Also the premonitory symptoms and photophobia improved significantly on naproxen sodium and significantly less rescue analgesics were required. Patients suffering from common migraine had less severe headaches and photophobia when taking naproxen sodium than when taking placebo and the headaches were shorter in duration and patients took less rescue analgesic. No significant difference was observed between the treatment groups in patients with classical migraine. Ten patients in the placebo group and six in the naproxen sodium group reported side-effects but these were possibly related to the use of rescue medication. Naproxen sodium proved safe and effective in common migraine attacks, but in this study efficacy was not established for classical migraine.