ABSTRACT Developing effective physical fitness exercise program for students is a strategy for improving student’s Academic achievement (Ehrlich, 2008).The purpose of this study was to investigate the effect of 12 weeks health related physical fitness exercise on student’s Academic achievement. The study employed Experimental research design.From grade 11 female 98 total population, 34 samplestudents were selected with the age of (EG=17.71±1.160, CG = 17.65±1.115) and divided randomly into 2 equal groups. Both the EG( n = 17) and CG(n = 17) participated in the typical one classes of 40-minute Physical education per week, but only EG were participated in additional 3 sessions per week of 60 minutes per session of fitness training.Pre and post test results of the selected fitness variables were taken from both groups. Cardio respirator fitness was measured using 12 minute run test, Body Composition variables were tested by BMI, Muscular endurance were tested using 900 push-up, Muscular strength were measured by using Wall-sit test, and flexibility were measured by sit and reach test. The data collected from the study subject was analyzed using SPSS version 23 software.By using paired t-test the mean differences/changes from pre to post test results of the variables and students average score changes from first to second semester were checked and Pearson correlation with level of significant at 0.05. The results showed health related physical fitness components such as CVE (MD=185.83), ME (MD=3.292), MS (MD=8.18), and Flexibility (MD=1.47) were improved significantly following the 12 week fitness Exercise in EG at (p<0.05). Besides, body mass index (MD=-0.200) were significantly reduced, since (p<0.05). But, no significant fitness improvement were found in all selectedvariables of CG (p>0.05). Furthermore, the correlation of most health related fitness components of EG such as cardiovascular endurance(r=0.79, p=0.037) and flexibility(r=0.583, p=0.014) have high and moderate positive statistically significant relationship with students average score respectively, while body mass index(r=-0.261, p=0.012) have low negative significant relationship with students Academic achievement. But, Muscular endurance(r=0.125, p=0.634) and muscular strength(r=0.019, p=0.941) have no statistically significant effect on students academic achievement. However, health related physical fitness components of the CG have no significant effect on student’s Academic achievement in all selected fitness variables. Therefore the null hypotheses were rejected in case of cardiovascular, body composition, and flexibility fitness variables, and accepted in case of muscular strength and muscular endurance. Finally, the researcher concluded that most health related physical fitness components have a significant effect on students academic achievement following the twelve week health related physical fitness exercises.