The therapy of hemorrhagic symptoms and the prevention of subsequent chronic disability in patients with hemophilia A and B are based on the appropriate use of specific concentrates of the deficient blood-clotting factors. The proper amount of the factor to infuse is calculated on the basis of the following parameters: patient's weight; type, location and severity of the hemorrhage to be controlled or prevented; biological half-life and yield of the infused factor. The elaboration of the therapeutic regimens to be followed in specific clinical situations is based on the above-mentioned parameters, which are fully discussed in this review. However, in the overall approach to hemophilia care, there are various other aspects, apart from strictly pathophysiological considerations. There are psychological, social and practical aspects which account for a number of specific proposals for therapeutic procedures to be used in certain circumstances (all discussed in the present report) and which should be considered separately. An example of the above is home therapy of hemophilia, which is fundamentally based on the observation that hemarthroses and hematomas account for over 90% of hemorrhagic episodes, with an average frequency of approximately 40 episodes/year/subject. It is therefore clearly understood that only early administration of specific concentrates will effectively prevent chronic joint damage, still the main cause of disability in the life of the hemophiliac. Annual average consumption of concentrates per patient is principally linked to the therapy of this type of hemorrhage and is, in turn, also influenced by the minimum effective dose for treatment of single episodes. Although this problem has not been completely solved, there is sufficient consensus that administration of 250 IU of concentrate (factor VIII or IX) in children and 500 IU in adults is effective, providing that hemarthroses and muscle hemorrhages are of a minor degree and are promptly treated. This approach leads to an average annual individual consumption of approximately 10,000 IU in children and 20,000 IU in adults, only for these episodes. A therapeutic regimen which is being increasingly used consists of treatment of acute synovitis with brief periods of prophylactic administration of concentrates (1-3 months), with the intention of interrupting the hemarthrosis-synovitis vicious circle and to allow for physiotherapy to avoid synovectomy.(ABSTRACT TRUNCATED AT 400 WORDS)