The purpose was to compare the short-term cost-effectiveness of intensive vs conventional education and supervision for the self-management of mild asthmatic patients. Consecutive newly diagnosed asthmatic patients (n = 162) were randomized into an intervention group (IG) and a control group (CG) with 1 yr of treatment and follow-up. Intensive education was given to 77 patients at visits every third month in the outpatient clinic. Eighty CG patients received conventional education and advice at the baseline visit only. All patients received similar inhaled anti-inflammatory treatment. At baseline and at 12 months standard clinical lung functions and health-related quality of life (HRQOL) were measured, the latter by the disease-specific St George's Respiratory Questionnaire and the generic 15D. Furthermore, the use of extra health care services, medication and sickness days were recorded. The IG experienced a significant improvement in all clinical and HRQOL outcome variables. The same applied to the CG except spirometric values. The groups differed significantly only in terms of FEV1 (P < 0.05) in favour of the IG. There was a significant difference between the groups in extra costs. The mean cost was FIM 2351 per patient (294 Pounds sterling) in the CG and FIM 2757 per patient (345 Pounds) in the IG, of which the intervention cost was FIM 1978 per patient (247 Pounds). In 1 yr follow-up the intensive education programme did not prove to be cost effective but was dominated by the conventional one regardless of what effectiveness measure was used. Also, a purely monetary cost-benefit calculation showed that the intervention resulted in a negative net benefit (loss) of FIM 406 per patient (51 Pounds). A longer follow-up may be needed before definitive conclusions about the cost-effectiveness of this kind of intervention can be drawn.