The purpose of this study was to perform a cost-effectiveness analysis of the structured treatment and teaching programme for patients with asthma (ATTP) at Dusseldorf University. We investigated whether the monetary benefits outweighed the costs of the intervention. Adult patients with moderate to severe asthma participated in a 5 day in-patient programme. Follow-up was 3 yrs. The incremental costs and benefits of the intervention, compared with standard treatment, were calculated. Costs were incurred by the hospitalization and by lost productivity. Compared to the year before the programme, (average reduction) days spent in hospital (5.2 days per patient per year), days of absence from work (18.4 days per patient per year), acute severe asthma attacks (3.8 attacks per patient per year), and physician consultations (2.3 visits per patient per month), decreased in the 3 yrs after the intervention. The programme produced net benefits of DM 12,850 (in 1991 German marks) per patient within 3 yrs. Within the health care sector, the net benefits were DM 5,900. Within 3 yrs, the paying bodies saved DM 2.70, and society as a whole saved DM 5 on each DM spent for the programme. We conclude that the intervention produced net monetary benefits. This result was stable over a wide range of variation of the outcome measures. Therefore, the programme deserves implementation, not only for its demonstrated medical benefits but also for its economic savings.