The aim of the present study was to examine the effects of a course of aerobic exercise on pulmonary function and tolerance of activity in asthmatic patients. Among the asthmatic patients, 36 patients (M= 16, F= 20) were chosen after clinical examinations, pulmonary function test, skin prick test (SPT) for aeroallergen and a six minute walk test (6MWT) on their own free will. A patient was said to have Exercise Induced Asthma (EIA) when he/she fulfilled the following criteria; (1) FEV1 less than 80%, (2) 12% increase or more in FEV1 or PEF after short-acting ss2 agonist prescription and (3) 15% decrease in FEV1 or PEF after 6MWT with 70% or 80% of maximum heart rate. The patients were randomly put into two groups of case (M=8, F=10, Mean age=27) and control (M=8, F=10, Mean age=29). Case group participated in eight-week aerobic exercise plan, while control group had no plan of exercise. Pulmonary function tests were done before and after the course of exercise. There were significant changes in FEV1, FVC, PEF, FEF25-75%, MVV, RF and 6MWT between asthmatic patients of the two groups (P less than or equal to 0.05), but FEV1/FVC showed no significant change. Mean of changes in FEV1, FVC, PEF, FEF25-75%, MVV, RF and 6MWT were -25.56, -17.19, 32.09, -27.93, -22.18, 5.63 and -307.5 in case group respectively while they were 6.2, 4.67, 1.96, 6.65, 15.56,-2.87 and 18.78 in the control group. This study shows that aerobic exercises in asthmatic patients lead to an improvement in pulmonary functions. Aerobic exercise rehabilitation can be a complement to medical treatment of asthma.