The objective of this study was to evaluate a structured treatment and teaching programme for adult patients with moderate to severe asthma. The design consisted of a prospective, before-after trial: the same consecutive patients were studied before and after intervention with observation periods 1 year before and 1 year after intervention. The investigation took place within a tertiary care centre (university hospital). A total of 142 consecutive patients were referred for in-patient treatment of their asthma, of whom 132 (93%) patients participated in the follow-up examination. The intervention consisted of a structured 5-d in-patient treatment and teaching programme presented by a specialized nurse educator. The aim of the programme was for the patient to assume greater responsibility for disease management, including self-monitoring of peak expiratory flow and qualified self-adaptation of drug therapy. The main outcome measures were the frequency of severe asthma attacks, hospitalization, and absenteeism from work (data provided by health insurance companies), patients' compliance and management skills. During the year before and the year after the intervention 71% and 36%, respectively of patients had one or more severe asthma attacks (mean difference 35%, 95% CI: 25-45%, P less than 0.0001). The percentage of patients who were hospitalized because of asthma decreased from 39% to 22% (mean difference 17%, 95% CI: 7-27%, P less than 0.002). The percentage of employed patients (n = 67) who were absent from work because of asthma decreased from 60% to 43% (mean difference 17%, 95% CI: 4-30%, P less than 0.04). The patients' adherence to maintenance drug therapy and their management skills improved significantly. It was concluded that the participation of patients with moderate to severe asthma in a structured treatment and teaching programme resulted in a substantial reduction in asthma morbidity in the year following the intervention.