Arterial blood gas analysis, including oxygen and carbon dioxide tensions, pH and bicarbonate were measured in 16 asthmatic patients during acute attacks of bronchospasm in Korea General Hospital. Hypoxemia was observed in 13 subjects of 16 cases and the mean value of the oxygen tension was 84.3mmHg. The decreased carbon dioxide tension was observed in 11 subjects with 1 subjects of the hypercarbia which is observed in severe degree of airway abstruction. The mean value of carbon dioxide tension was 32.6mmHg. The respiratory alkalosis was observed in most of all subjects except 1 case of severe mixed acidosis. There were minimal changes in bicarbonate values except 1 severe subject. History of asthma and duration of the acute attack were unrelated to the alterations in blood gas tension and severity of airway obstruction. In conclusion, the characteristic blood gas pattern of the clinically less severe asthma is hypoxemia and hypocarbia associated with respiratory alkalosis, we observed.