Abstract
The factor VIII clotting activity (VIIIc1 and factor VIII related antigen (VIIIRAg) were determined repeatedly in 24 pairs of age-matched normal women, one of each pair being on oral contraceptives. No significant differences in either parameter or in the VIIIc/VIIIRAg ration were found between the two groups ,although the mean factor VIII clotting activity and VIIIc/VIIIRAg ratios for women on oral contraceptives were very slightly higher than for those not on oral contraceptives.