A randomised controlled trial, involving 112 adolescents with asthma, and a 2-year follow-up was conducted to assess the impact of an intervention programme aimed at enhancing adherence to asthma medication. This programme had a duration of 1 year and consisted of an experimental group which received usual care from a paediatrician, but additionally attended individual and group sessions with an asthma nurse, and a control group which received usual care only. The programme aimed at enhancing adherence by stimulating a positive attitude, increasing feelings of social support, and enhancing self-efficacy. At baseline, and after 12-month (T1) and 24-month (T2) follow-up, the participants filled in questionnaires which were based on the concepts of the ASE-model. Adherence was assessed by self-report (range: 1-10) at the same points in time. After 12 months, 97 adolescents (87%) were available for follow-up, decreasing to 86 adolescents (77%) after 24 months. No statistically significant differences were found between the control and the experimental group, except for one. At T2, self-reported adherence appeared to be statistically significantly higher in the experimental group. In conclusion, there seems to have been no substantial effect of the intervention programme. Copyright © 2001 Elsevier Science Ireland Ltd.