It has been reported that migraine is common in systemic lupus erythematous (SLE) and an association with phospholipid antibodies has been suggested. The incidence of migraine and non-migrainous headache was prospectively studied in 90 patients with SLE and 90 age- and sex-matched controls. A history of migraine was commoner in SLE patients than in controls [31(34%) vs 15(16%); P less than 0.05], and the mean age of onset was higher in the SLE group (26.8 vs 17.2 years). Within the SLE group an association was found between migraine and SLE disease activity. Non-migrainous headaches were also more common (non-significant) in the SLE group, and there was a close temporal relationship between onset of both headache and SLE in many patients. Both migraine and non-migrainous headaches in SLE patients often responded to specific SLE treatment. No association was found between migraine or other headaches and antibodies to phospholipids.