Regular physical activity can have immediate health benefits by positively affecting cardio-respiratory, muscular fitness, and body composition improvement. The main interest of the present study was to evaluate aerobic exercise and its effects on students' physical fitness level. The study design was a quasi-experimental method. 40 female students of Lalibela preparatory school aged 18-22 years had divided randomization into 2 equal groups, experimental (n=20) training group who performed in 3 days/week for 3-month aerobic exercise training program such as walking, jogging, running and rope skipping and a control (n=20) group however, did not perform this selected aerobic training unless both groups undergone normal physical education class program. Both groups had pre- and post-testing, and all subjects took four physical fitness tests: cardio-respiratory fitness was measured with a 12 minute cooper test, muscular endurance was measured with a 900 push up test, flexibility was measured with a sit and reach test, and body composition was measured with Body Mass Index. The collected data was analyzed using a statistical method with a paired t test level of significance of 5%. The result of the adjusted posttest mean revealed that significant improvement in experimental group cardio-respiratory fitness (MD = 607.50m), flexibility (MD = 5.525) and Body Mass Index (MD = 1.124) and muscular endurance (MD = 2.650) had been shown compared to the control group. Generally, the present study concluded that aerobic exercise training had a significant effect on students’ physical fitness. Hence, aerobic exercise was effective and beneficial effect for the enhancement of female students’ physical