PURPOSE: The purpose of this study was to compare high-resolution CT(HRCT) findings of asthmatic and control subjects, and to evaluate the relationship between HRCT findings and clinical features in asthmatic subjects. MATERIALS AND METHODS: Using HRCT, we studied 16 asthmatic and 16 control subjects. We analyzed the ratio of bronchial wall thickeness, the frequency of bronchial dilatation, the presence of emphysema, centrilobular nodule, and pulmonary infiltration in two groups. In addition, we assessed HRCT findings of asthmatic patients for correlation with clinical findings and the pulmonary function test. RESULTS: The ratio of bronchial wall thickness of 16 asthmatic subjects (0.48 ±0.08) and 16 control subjects(0.40 ±0.08) was significantly different in statistical analysis (P<0.001). Bronchial dilatation was seen in 53(32%) of 165 bronchi in the asthmatic group and in 16(13%) of 119 bronchi in the control group, which was statistically significant (p<0.01). Among 16 asthmatic patients, there were eight cases of emphysema, two of centrilobular nodule, and four of pulmonary infiltration. The ratio of bronchial wall thickeness of eight asthmatic subjects with emphysema(0.47 ±.08) and eight such subjects without emphysema(0.49 ±0.09) was not significantly different when statistically analysed. In asthmatic patients, HRCT findings did not correlate with clinical findings and the pulmonary function test. CONCLUSION: On high-resolution CT, the ratio of bronchial wall thickness and the frequency of bronchial dilatation between asthmatic and control subjects are significantly different.