This paper describes experience over an 18-month period of a new preparation of factor VIII, cryoprecipitate, prepared by the Regional Blood Transfusion Service from human plasma. This relatively simple and inexpensive method selectively extracts the factor VIII leaving behind the other blood products for use in other ways. Replacement therapy in the treatment of haemophilia has been generally regarded as inadequate due to the difficulty in obtaining potent antihaemophilic globulin in sufficient amounts, and cryoprecipitate represents a useful advance. Bleeding episodes in 25 patients with factor VIII deficiency have been treated with cryoprecipitate on 41 occasions and an assessment of the haemostatic effect of this material has been made in treating haemarthrosis, muscle haematomata and the management of major and minor surgical operations. Routine follow-up over a 6 month period was undertaken to determine the incidence of side effects. Two cases of hepatitis were found, possibly resulting from cryoprecipitate therapy. However, both patients had also received blood or fresh frozen plasma and the source of the hepatitis virus must remain in doubt. No factor VIII inhibitors were found despite repeated courses of therapy in several patients. The advantages and disadvantages of cryoprecipitate are set out and its encouraging place in the management of haemophilic bleeding assessed.