Background and Aim: Aerobic exercise plays an important role in prevention of obesity, improvement of sleep quality and cardiovascular function. The purpose of this study was to investigate the effects of 8 weeks of moderate-intensity aerobic exercise training on sleep quality, and also cardiac structure and function in inactive obese girls. Materials and Methods: In this study, 20 inactive obese girls (mean age; 18 year, mean BMI ≥ 30 kg/m 2 ) participated voluntarily and were randomly assigned to exercise (E, n=10) and control (C, n=10) groups. Exercise group participated in aerobic exercise program for 8 weeks (60 min/day, 3 times/week, 50%-70% maximal heart rate). Control group maintained their daily routine physical activity for 8 weeks. At baseline and after 8 weeks of the training program, both groups were evaluated for cardiac function and structure, and also sleep quality by use of echocardiography and sleep quality questionnaire respectively. T-test and Pearson correlation coefficient were used for data analysis. p≤0.05 was considered significant. Results: Sleep quality improved significantly in the exercise group compared to that in the control group (p ≤ 0/05). Among cardiac structural and functional indices, only cardiac output significantly increased in exercise group compared to that in the control group (p ≤ 0/05). Conclusion: 8 weeks of moderate intensity aerobic exercise training improved sleep quality in inactive obese girls. However, except for cardiac output, it did not create any significant change in other cardiac structural and functional indices.