It is well known that teenagers with chronic diseases have problems complying with their treatment. The aim of this study was to evaluate the patient's knowledge of haemophilia and his compliance to prophylactic treatment, and the age at which the patient took over the responsibility for his disease and to create educational material for teenagers and adolescents. This was a prospective multicentre study performed in Hemophilia Treatment Centres in Scandinavia. A total of 108 of 134 patients, between 13 and 25 years completed the questionnaire, a response rate of 80%. Eighty-three patients had a severe form of haemophilia, 24 patients in moderate form and one patient did not know the severity of his disease. Seventy-eight patients were on prophylactic treatment. The median age for starting prophylactic treatment was 3.0 years and the median age for the patient performing venepuncture was 11.6 years. Sixty-seven of 78 patients knew that the best time to give prophylactic treatment was in the morning. Even though the patients were on prophylactic treatment, 47 of 78 patients took additional treatment before sports activities. At a mean age of 14.1 years the patient himself had the responsibility for his disease and treatment. In the cohort of 108 patients, 73 were aware of their haemophilia heredity. This study shows a rather high degree of knowledge of haemophilia and compliance with treatment among the patients but it is of great importance for the nurse to continuously improve the patient's compliance and keep him aware of the benefit of regular treatment for his future well being.