OBJECTIVES: To evaluate the impact of the 2002 guidelines on the current status of prophylaxis in French children with severe hemophilia A or B. STUDY DESIGN: Clinical information was captured, in a prospective way, using FranceCoag Network. We retrospectively studied 291 patients with severe (<1 IU/dL) hemophilia A and B, with no history of inhibitors. RESULTS: Our results demonstrate that the availability of national medical guidelines has improved clinical practice in France. In the past decade, the proportion of children with severe hemophilia undergoing prophylaxis has shown a significant 2- to 3-fold increase: <80% of these children >3 years of age are now receiving prophylaxis. In severe hemophilia A and B, the age at which prophylaxis commences has significantly decreased: 4.0 and 6.1 years for the period 1996-1999 as opposed to 1.8 and 1.4 years for the period 2004-2007 (P = .0001). CONCLUSIONS: Long-term clinical and physical evaluations of patients will be necessary to establish the benefits of this increase in prophylactic treatment on the prevention of hemophilic arthropathy. (R.A.)