Costs of drugs used for the treatment for 1 year were compared before and after spa therapy in 16 patients with asthma in relation to disease severity. Asthma severity was classified as : stage 1 (intermittent), 2 (mild persistent), 3(moderate persistent), and 4(severe persistent). 1. The total cost of drugs used for each pa-tient for 1 year clearty decreased in all groups. The % decrease of the costs of drugs in each group was 27.2% in patients with stage 1, 43.5% in those with stage 2 and 34.1% in those with stage 3-4 (mean 34.5% ). The reduction of the cost of bronchodilators was predominant in patients with stage 3-4, and the decrease in the cost of corticosteroids predominant in those with stage 2. The reduction of costs of antiallertgics, mucolytics, and antibiotics was predominant in patients with stage 2 and stage 3-4. The % reduction in the cost of corticostroids was remarkable in patients with stage 2. The % decrease in the costs of mucolytics and antibiotics was predomi-nant in patients with stage 2 and stage 3-4. The results obtained here suggest that the costs of drugs used for asthmatics could be reduced by long-term spa therapy, and the reduction of the costs was larger as asthma stage became more severe.