The occurrences of factor V Leiden mutation (Arg506Gln) and antiphospholipid antibodies (APA) in migraine patients have been reported, but the findings are controversial. We investigated the presence of factor V Leiden and the serum level of anticardiolipin antibodies (aCL) in a consecutive series of 70 migraine patients (47 women; mean age, 34.1 years). Of these, 40 patients had migraine with aura. A matched sample of 70 healthy people was considered as the control group. Heterozygous genotype for factor V Leiden mutation was detected in 4 (5.7%) migraine patients (of which 2 had migraine with aura) and in 2 (2.8%) subjects of the control group. Although proportionally more migraine patients harbored the factor V Leiden mutation, this difference was not statistically significant, perhaps due to the small number of patients involved. We found normal serum levels of aCL in all migraine patients. Further studies and a long-term follow-up are warranted to determine the significance of this genetic abnormality in migraine.