Prophylaxis, or the practice of routine replacement infusions of clotting factor concentrate in persons with severe haemophilia, is a demanding medical regimen. Prophylactic infusions require direct venepuncture or sterile entry into a central venous access device on a regular basis. A telephone survey was conducted to elicit information regarding the barriers to compliance with prophylaxis. The Mountain States Regional Haemophilia and Thrombosis Center has recommended prophylaxis to 52 male patients with haemophilia A or B. The haemophilia nurse attempted to contact all of these patients or their parents, and contact was made with 38 (73.1%) of them. Respondents were asked about the following issues: their decision to initiate prophylaxis; their self-rated compliance; the challenges, barriers, and facilitators of prophylaxis; and their perceived value of the therapy. Four patients (10.5%) elected not to begin prophylaxis. Of the 34 persons who began prophylaxis, 20 respondents (58.8%) rated their compliance as excellent. Nearly one-third of the families with excellent compliance (giving 75-100% of prescribed infusions) stated that the time-consuming nature of prophylaxis was the most significant challenge of the regimen. In addition, 58.3% of the families that gave less than the prescribed number of infusions reported that the time commitment was the primary reason for missing infusions. Knowledge of the benefits of prophylaxis was the primary facilitator of compliance for 44.1% of families. Ninety-seven percent of respondents rated prophylaxis as very valuable. These data show that despite the known benefits of prophylaxis, it is a demanding medical regimen, and compliance is imperfect. In addition, this study underscores the importance of providing continuing support and education for patients and families who are implementing prophylaxis.