OBJECTIVES: Treatment of severe hemophilia patients has considerable economic implications, especially with increased use of prophylaxis. Few studies have analyzed the total costs of treatment, hence we undertook this study. METHODS: To determine total costs and trends of treating children with severe hemophilia-A from 1978 to 1998, at the Hospital for Sick Children in Toronto, one patient chart reviewer identified resource consumption of all patients (n=17). For each patient, costs for factor concentrate, clinic visits, physicians and healthcare professionals (physiotherapists/social workers), laboratory and other tests (x-ray, MRI, ultrasound) and hospitalizations were determined. Costs in Canadian dollars were taken from standard lists and discounted at 3%. RESULTS: Total average cost (range) was $69,322 ($14,471-$108,294)/year/patient of which the largest part, $65,184 ($8,250-$107,104), 94% (57%-99%) was accounted for by Factor-VIII. Hospitalizations accounted for $2,396 ($0-$57,063)/patient/year including drugs, nursing care and stay. Clinic visits and physician visits were $1290 ($122-$4143) and $177 ($0-$308), respectively. Healthcare professionals averaged $89 ($0-$252) and lab tests and other tests cost $156 ($26-$226) and $31 ($4-$70)/patient/year, respectively. The average number of bleeds was 12.9 (2.0-22.0)/patient/year. Since 1978, the average number of bleeds decreased by 0.71 (r2=0.56)/patient/year. The average number of hospitalizations was 0.21 (0-4)/patient/year, in which patients stayed on average 10.7 (1-135) days. Since 1984, the number of hospitalizations has decreased by 0.5 hospitalizations/patient/year (r2=0.74). Concurrently, the average costs of the treatment of severe hemophiliacs have increased by approximately $3740 (r2=0.62)/patient/year. Clotting factor concentrate cost per patient increased by $4215 (r2=0.66)/year, of which prophylaxis accounted for $1429 (r2=0.60)/year, while on demand Factor-VIII costs decreased by $497 (r2=0.16)/year. CONCLUSIONS: The annual cost of hemophilia care, of $69,322 per patient, is substantial. The number of bleeds and hospitalizations is decreasing while there was a clear trend in increasing costs of treating severe hemophiliacs, primarily associated with increasing use of prophylactic treatment.