Effect of free swimming training in the hot spring pool (30℃) on ventilatory function were observed in nine patients with intractable asthma by measuring FVC, FEV(1.0), PEFR, MMF, V(50), V(25). 1. Swimming in the hot spring pool for three months allowed the reduction of glucocorticoid used for their asthma attack. 2. Although FVC was not affected by swimming training, EEV(1.0), PEFR, MMF, V(50), V(25) which represent obstructive ventilatory function were gradually improved by swimming training. The results show that free swimming training in the hot springpool is clinically available in intractable asthma.