Abstract: This study investigates the effect of ergometric exercise on F-VIII activity in mild and moderate haemophilia-A. The last study in this field was done in 1984. Despite of many results on healthy individuals and cardiac patients, the effect of exercise on coagulation parameters in bleeding disorder patients has not been well studied. 10 haemophiliacs (mean 24.5 year) were exercised on a bicycle ergometer according to Accepted Paediatric Protocol lasting 23-46 min. Blood samples were drawn before, 8 and 45 min post exercise. The average activity of F-VIII:c increases to 30.32 and 22.29% eight and 45 min post exercise, respectively. Increase of F-VIII: c activity was more pronounced in mild patients. Reduction in PTT, 45 min. post exercise, increase in vWF activity 8 min post exercise and increase in vW: Ag in both stage in to recovery were significant. It is concluded that ergometric exercise induce increase in F-VIII: c activity in mild and moderate haemophiliacs. Offering a suitable exercise programme in hemophilia-A not only improves their musculoskeletal system status but also increase F-VIII:c. Replacement therapy of factor deficient plasma is a kind of injective prophylaxis in severe haemophiliacs and exercise could be a suitable prophylaxis in mild and moderate haemophiliacs which could reduce the need of factor replacement therapy in these patients.