Background: Recurrent miscarriage and infertility are intriguing problems with growing clinical concern.Among the causes of thrombophilia; elevated plasma VIII:C activity level emerges with a rising concern as a possible risk factor of repeated miscarriage and subsequent infertility.Factor VIII is activated in the intrinsic pathway of coagulation cascade of secondary hemostasis. Objective: To evaluate plasma VIII: C activity level in females with repeated miscarriage and primary unexplained infertility in order to determine if Factor VIII:C over-activity is a probable cause of such conditions. Patients, Materials and Methods: This study was performed on strictly selected90 females, aged 20-45 year. The females wereassignedinto three groups (34 females with unexplained primary infertility, 41 females with history of repeated miscarriage(after exclusion of other gynecological and obstetrical causes) and 15 healthy age-matched females were selected as a control group. Plasma VIII:C functional activity was assayed.Blood samples for general hematological studies (Packed cell volume PCV, Prothrombin time PT, and activated partial thromboplastin time APTT) were obtained manually for all included females. C-reactive protein assayed in all samples to exclude the inflammatory causes of elevated factor VIII, which is regarded as an acute phase protein. Results: Factor VIII data were expressed as a mean of percentage of activity (±SD). A significant (*p=0.009) higher plasma activity level of factor VIII:C was demonstrated in infertile females(111.29%±31.66) and females with recurrent abortions (118.63%±39.54); Compared with the healthy control females (80.23%± 22.23), PCV, PT and PTT measurements demonstrated no statistical significance in infertile and recurrent abortion groups when compared to the control group (p>0.05). There was no statistically significant difference between the three groups regarding the PCV, PT and PTT measurement. Conclusions: Plasma Factor VIII:C activity level was higher in females with unexplained primary infertility and those with history of recurrent abortion. This elevation suggested of being independent risk factor of such conditions; after exclusion of other multiple causes leading to thrombophilia, abortion and infertility.