Introduction - As part of the FranceCoag Network project, a prospective cohort (the FranceCoag Cohort) of patients with inherited coagulation disorders (ICD) was launched in January 2003 with the primary objective of comprehensively describing the geographic distribution, characteristics, and clinical course of this population. This project also aims to serve as a public health surveillance tool, enabling rapid investigation of any suspected transmission of a new pathogen via replacement therapies. It succeeded the National Therapeutic Follow-up of Hemophiliacs (SNH), which was launched in 1994 in the wake of the contaminated blood scandal. Method - This is a prospective, open-label, multicenter cohort comprising patients with hemophilia (A or B) or a severe deficiency of another coagulation factor. Patients are enrolled by specialized treatment centers, and follow-up is purely observational, involving the collection of demographic, clinical, genetic, and biological data using standardized forms. Results - As of the date of analysis (October 8, 2005), 4,018 of the estimated 6,000 patients had been enrolled from 38 hemophilia treatment centers (HTCs). The diagnoses were hemophilia A (n=2,901, including 1,306 severe cases), hemophilia B (n=605, including 229 severe cases), von Willebrand disease (n=375), and a deficiency in another coagulation protein (n=137). This analysis reviews several health outcomes: viral infections (19.5% of patients with severe hemophilia are carriers of the human immunodeficiency virus (HIV) and 51% of the hepatitis C virus (HCV)), the development of inhibitors to one of the coagulation factors (11.3% of affected patients), and mortality (62 deaths were reported, including 30 cases related to viral infection). Patient management appears to depend on the type of deficiency and its severity. Discussion - This cohort opens up several avenues for further research, notably: the study of the determinants of inhibitor development, the causes of patient mortality, and the management of HCV-positive patients. (R.A.)