Ipratropium bromide(IP) is a new anticholinergic bronchodilator To evaluate its effect on bronchial asthma which is still unkown in Korea, a double blind and randomized study was done on all patients of bronchial asthma who visit out-patients clinic of our department from June to September 1987 and showed 75 to 100% of FEV1 / FVC ratio (On pre bronchodilator 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. On 5 minutes, effect of FE was significantly greater than IP.(FVC p<0.05, FEV1 p<0.01) 3. On 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.