BACKGROUND AND PURPOSE: Physical inactivity is a leading cause of obesity among Childhood and adolescent that continuous leads to an increased risk for cardiovascular diseases. The purpose of the study is to check the effect of aerobic exercise on body composition in obese adults. METHODS:Thirty obese subjects aged 25–35 years were included in the study.The subjects were conveniently divided into two groups each comprised 15 patients each. All the subjects were assessed for body mass index and waist hip ratio using weighing machine and inch tape respectively. The mean and standard deviation for the variable BMI and WHR of the subjects for Group A were 32.63±1.72,31.51±BMI and WHR of the subjects, for Group B the values were 31.86±2.23,31.86±2.31 and 1.08±0.15,1.08±0.15 respectively. Group A is an experimental group and Group B is a control group. Group A was given aerobic exercise on treadmill and for Group B was given no intervention. The anthropometric measurements were taken for both the groups on the first day and after the completion of four weeks. RESULTS: All the subjects completed the four week aerobic exercise programme .For Group A , the variable body mass index showed statistically significant improvement within the group (p <0.05) where as variable waist–hip–ratio did not show significant improvement within the group(p> 0.05). For group B, these variables showed insignificant changes within the group.On the otherhand, the BMI showed insignificant differences (P<0.05) and waist–hip ratio showed significant differences(p<0.05)between the groups. CONCLUSION : These findings revealed the effectiveness of aerobic exercises in reducing body mass index and waist –hip ratio in obese adults.