Abstract: The main objective of this study was to investigate the relationship between physical fitness and academic achievement among Model School students of Haramaya University. For this purpose Grade six students’ physical fitness levels were compared to their academic achievement based on the idea that health related physical fitness had an impact on the ability to achieve academically. The pre and post tests on selected health related physical fitness parameters were administered for two groups (experimental group and control group). For academic achievement the first semester GPAs (grade point average) was taken as pre test and Second Semester GPAs was taken as post test for both groups. The GPAs of the groups was determined by calculating an average of all subjects. Data was collected from 20 students (10 boys and 10 girls) grade six sections A and B with aged 11-13 years old, during the 2012-2013 school year by using the health related Physical Fitness Tests and (GPA‘s). The training schedules were for twelve weeks for physical fitness exercises and it was arranged between the first semester final exam and Second Semester final- Exam.