We conducted a multicentre, cross- sectional study of 1042 haemophilia subjects across Europe to compare various health outcomes associated with on-demand vs. prophylactic factor-substitution therapy. Demographic, medical history, and healthcare resource utilization data were analysed along with the number of bleeding events over the past 6 months. Treatment-cost data were also examined to provide preliminary information for future economic studies. A logistic regression analysis, controlling for other statistically significant covariates, showed that patients treated on demand were 3.4 times more likely to have had a joint bleed over the previous 6 months than those treated with prophylaxis. Multiple regression analyses further confirmed these findings, because on-demand subjects had, on average, 5.15 more joint bleeds over the reporting period than patients treated with prophylaxis. Notably, these findings were even more dramatic for younger haemophilia patients when our study sample was stratified by age. Due to the high cost of factor replacement, healthcare costs were significantly higher for subjects treated prophylactically. While hospital costs for prophylaxis subjects were, on average, lower, statistically significant cost savings for prophylactic subjects were not noted. These results suggest that clinicians and health policy decision-makers should consider the advantages of prophylactic therapy for haemophilia patients in formulating treatment protocols and allocating health resources.