Attendances at the Regional Haemophilia Reference Centre in the Edinburgh Royal Infirmary have been analysed over a period of five years from 1969 to 1973. Of 77 patients registered in 1969, 64 had haemophilia A (factor VIII deficiency) and 13 had haemophilia B (factor IX deficiency). In 1973 the numbers were 68 and 14 respectively. An increased attendance at the Centre from 123 in 1969 to 624 in 1973 was noted. This was due to patients reporting earlier and more frequently for outpatient treatment of haemarthroses which occurred with the greater availability of supplies of factor VIII. The number of admissions for inpatient treatment did not change significantly over the period. Haemarthrosis of the knee was the commonest dominant lesion. The amount of replacement therapy in the form of fresh frozen plasma, cryoprecipitate, antihaemophilic fraction, and factors II, IX, and X concentrate used in the Centre (ie, excluding that used for elective procedures) increased from 2704 donor units in 1969 to 8778 donor units in 1973, the main increase being in cryoprecipitate. The number of factor VIII units used per patient attending per year, for both elective and emergency treatment in haemophiliacs, is recorded and discussed as are its effects on the treatment patterns of patients and the implications for the future.