The effects of a pharmacy-based intervention on the knowledge and attitudes of asthma patients was studied with a small convenience sample in four Finnish community pharmacies. The intervention consisted of patient education, counselling and outcomes monitoring according to Therapeutic Outcomes Monitoring (TOM) concept. Twenty-eight patients aged 20-64 years suffering from asthma and having problems in asthma management were involved. Measurements were done at baseline, immediately after the intervention (12 months) and 1 year after the intervention (24 months) using a pre/post-test design, with the patients being their own controls. Both knowledge about and attitudes towards asthma as a disease improved significantly during the intervention. Also knowledge about medication improved significantly during the intervention, though the patients' attitudes towards the medication remained unchanged. The negative correlation between knowledge about and attitudes towards asthma (-0.35) at baseline disappeared after the intervention (0.21). There was a positive correlation between knowledge about and attitudes towards medication at 12 months (0.40, P=0.04) which was still significant 1 year after the intervention (0.40, P=0.04).