The purpose of this study was to investigate the effects of 12 weeks strength training on selected physical fitness performance of u-17 male soccer project trainees at Durbete Town. The total subject for the study were thirty (n =30) soccer trainees in Ethiopia 2014 E.C. Since the study populations were little, all were taken as a sample by using comprehensive sampling technique. Through randomization method trainees segregated in to two groups, an experimental group (N=15) and a control group (N=15). The experimental group (EG) performed twelve-week moderate strength training, 2 sessions per week (Tuesday and Thursday) for a total of 45 minutes and the control group (CG) did only their regular soccer training 3 days per week for 60 minutes duration. The data was collected through field tests (30-m sprint test for speed, Illinois Agility test for agility and Standing Long Jump test for power). The data were analyzed by using Paired sample t-test using SPSS version 25 with significance level of 0.05. Based on the analyzed data, the pre-posttest performance of EG were significantly improved their speed in 0.25 sec (5.62%) agility -0.47 sec (2.62%) and Standing Long jump 0.17m(8.17%). Generally, the results of this study show that 12 weeks of strength training improved speed, agility and power performance of u-17 male soccer project trainees. Therefore the study recommended that coaches should give concentration to strength training in coaching soccer and these training methods are recommended to soccer players for improving selected soccer related fitness performances. Key words: