Chloroquine was employed in treatment of bronchial asthma and clinical follow up performed in 634 cases, some of which had been observed for 4 years. 1) Clinical effctiveness was obtained in 91.3% of the patients with this treatment regimen and disappearance of asthmatic attack was observed in 42.7% of the all cases. 2) Equally effective results were obtained by this treatment regimen in all cases with asthmatic attacks in spite of many different factors of the disease such as sex, age, duration of the disease, type of the disease or symptoms. 3) Clinical therapeutic effectiveness was obtained within one month in most of cases and a positive correlation was noted between effectiveness and treatment duration. 4) To severely attacked patient, an excellent therapeutic results was obtained from the beginning of treatment by combined therapy with prednisolone, which was attempted to supplement the late effctiveness of chloroquine. 5) The patients resulting satisfactory course by long term administration of the drug were followed up by decreasing dosage or discontinuing of the drug, showing good result in most cases of them. 6) Side effects of the drug was minimal and transient. There were no discontinued cases by side effects. Main side effects were gastrointestinal, ocular and neurological symptoms. But this treatment regimen brought no detestable side effects on the hematopoetic organ, liver or retina. 7) The therapeutic effectiveness of this treatment was supported by improved pulmonary function tests of the patients. 8) Fate and organ distribution of chloroquine were observed in vivo. A constant plasma level was kept after one week administration of the drug, which was distributed in the liver, spleen and lungs in high concentration. The drug was disappeared considerably fast from plasma by discontinuation of administration. It is clear from above data that this is an excellent treatment of the bronchial asthma and long term oral administration of chloroquine with small dosage induces cure or improvement of the bronchial asthma, without any detestable side effects.