Many studies believe that regular physical activity can have immediate health benefits by positively affecting cardio respiratory fitness, flexibility and speed. The purpose of this study was to investigate the effect of calisthenics circuit training on cardio respiratory fitness, flexibility and speed variables. The design of this research was experimental method. Thirty male students of Birakat secondary school aged 15-16 years had divided randomly into 2 equal groups. Both the exercise group (n = 15) and control group (n = 15) participated in the typical 1 classes of 40-minute Physical education per week in schools, but only participated in additional 2 sessions per week of 40 minutes per session of exercise training, which comprised as jumping jack, wall sit, push up, abdominal crunch, squat, triceps dips, jumping rope, side lifts, side plank, step up, lung and plank. Both groups had taken pre and post-testing and all the subjects participated in physical fitness tests: cardio respiratory fitness was measured using 12 minute run and flexibility was measured using sit and reach test and speed was by 60 meter speed test. The collected data was analyzed using statistical method Analysis of paired t-test with level of significant 0.05. The results showed calisthenics circuit training significantly improved cardio respiratory fitness, flexibility and speed in at p>0.05 but in no significant change was observed in all the variables. Therefore this research confirmed as calisthenics circuit training could improve the cardiovascular, flexibility and speed of high school students. Hence the allocated physical education period in Ethiopian education system is very low and high school students should get additional times to improve their fitness and health.