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Background: Hemophilia is an X-linked heritable coagulopathy with an overall prevalence of approximately 1 in 10,000 individuals. Hemophilias are rare X linked hereditary bleeding disorders. Platelets may be among the determinants of variability in bleeding phenotype.Objective: To evaluate the platelet function tests in patients with hemophilia, and to explore the influence of platelet dysfunction on hemophilia bleeding score. Patients and Methods:The study was conducted on 40 hemophilic patients and 20 normal persons as a control in outpatient clinics at Kafr El-Sheikh Governorate Hospitals and Al-Azhar University Hospitals (Al-Hussein and Sayed Galal) to evaluate the platelet function tests in patients with hemophilia, and to explore the influence of platelet dysfunction on hemophilia bleeding score. Results:The majority of cases (35 patients 87.5%) were type A and (5 patients 12.5%) were type B. As regard to hemophilia scoring system (HSS), 3 patients (7.5%) were type 1, 19 patients (47.5%) were type 2 and 18 patients (45%) were type 3. Bleeding from the knee occurred in the majority of patients (77.5%), from the elbow occurred in 32.5%, from the ankle occurred in 5%, from the vagina occurred in 15% and from the nose and the gum occurred in 7.5%. Platelets and maual platelet count showed insignificant difference between both groups. Platelets aggregation tests (ADP) test, collagen and restocetin agonists test) were significantly lower in cases group than control group. Prothrombin time (PT), international normalized ratio (INR), bleeding time (BT) showed insignificant differences between both group. On the other hands, activated partial thromboplastin time (APTT) significantly prolonged cases group than control group. No hemophilia C cases were detected in our study. Conclusion:There was a statistical significant relationship between bleeding phenotype in hemophilia B and platelet function. Diagnosis of hemophilia was confirmed by factor VIII assay for hemophilia A and factor IX assay for hemophilia B.