Seventeen inpatients with bronchial asthma, including 15 steroid-dependent intractable asthmatics, received spa therapy (swimmimg tratning in a hot spring pool) for 3 months at Okayama University Medical School, Misasa Branch Hospital. Clinical effects of spa therapy on these patients were evaluated regarding patient age, age at onset of disease and each asthma type classified by clinical symptom. Spa therapy was markedly effective in 5 cases (29.4%), moderately so in 7 cases (41.2%) and slightly so in 4 cases (23.5%). Reduction of the corticosteroid dose was made possible in 12 patients (80%) out of the 15 steroid-dependent asthmatics. Spa therapy was more effective in patients over 41 years old and in patients whose age at onset was 21 years or over. Clinical symptoms were improved more in the asthmatic group with bronchiolar obstruction and with bronchospasm-hypersecretion than in cases showing only bronchospasm.