It has been reported that migraine sufferers have an enhanced platelet activity, as well as an enhanced thromboembolic risk. In this study, 12 subjects with classic migraine were compared with 12 age- and sex-matched controls. The following parameters were tested: platelet aggregation; platelet content of ADP, ATP and cyclic-AMP (cAMP); plasma levels of cAMP, 6-keto-PGF1 alpha and thromboxane B2, serum levels of TxB2 and lipids. ADP- and adrenaline-induced platelet aggregation, platelet content of ADP, ATP and cAMP did not differ significantly between the groups. Platelets from migraine subjects, however, showed a decreased beta-adrenoceptor response to stimulation with isoprenaline when determined as platelet cAMP production in vitro. The prostacyclin metabolite 6-keto-PGF 1 alpha was significantly decreased in the migraine group. No difference were observed in TxB2. Plasma lipids were similar, except that the migraine cases had higher levels of LDL-cholesterol. These data do not confirm a general platelet malfunction in migraine patients, but suggest a decreased functional capacity of platelet beta-adrenoceptors and an altered metabolism of prostacyclin and LDL-cholesterol.