The practice of prophylactic treatment of boys with severe haemophilia has been evaluated in our centre. Prophylaxis was started at the median age of 3.7 years (range 0.4-12.7 years) in 38/41 children (93%) under 17 years of age. Median follow-up was 4.1 years (range 0.4-12.7 years). The criteria of primary prophylaxis according to the definition by the European Paediatric Network of Haemophilia Management was fulfilled by 9/38 (24%). Although a majority [76%, 29/38] of the children started prophylaxis after a median number of joint bleeds of 3.5, 70% of the children in this group had clinical joint scores of 0. Intravenous catheter insertion was required at a median age of 15.5 months (range 5-36 months) in 21% of the children, resulting in a catheter infection rate of 1.74 per 1000 catheter days. None developed an inhibitor on prophylaxis and three patients who had low-titre inhibitors (< 5 Bethesda units) prior to prophylaxis had undetectable inhibitors after prophylaxis. The home-treatment training programme required considerable time and cost. As a result, 87% of the children used peripheral venous access and hospital visits declined as prophylaxis became established. Parents' incentives for prophylaxis were that the children undertook many physical activities and sports previously not recommended, there was less parental anxiety and an overall improvement in the quality of life for the whole family.