Ipratropium bromide (IP) is a new anticholinergic bronchodilator. To evaluate its effect on bronchial asthma which is still unknown in Korea, a double blind and randomized study was done on all patients of bronchial asthma who visit out-patients clinic of out department from June to September 197 and showed 75 to 100% of FEV1/FVC ratio on prebronchodilator spirometry (pre BD). The selected patients were given 2 puffs of Fenoterol (FE) or Ipratropium inhalator blindly and Spirometry. The repeated results are: 1. In both FE and IP groups, there was a significant bronchodilatory effect on 5 and 60 minutes after administration. 2. One 5 minutes, effect of FE was significantly greater than IP (FVC p<0.05, FEV1 p<0.01). 3. One 60 minutes, effect of IP was slightly less than FE but statistically non-significant. On the basis of above results, we concluded that onset of effect of IP is slower than FE, but its effect is significant and nearly comparable to FE.