The purpose of this study was to investigate the effect of twelve week resistance training on some selected physical fitness variables. The study was employed experimental research design from grade 11th male 257 total populations, 36 sample students were selected by using purposive and for EG and CG simple random sampling technique was used with age of (EG=18+ 0.686, CG=18+0.608) and divided randomly in to 2 groups. Both the EG (n=18) and CG (n=18) were participated in this study. From this experimental group were only participated in the resistance training 3 sessions per a week of 50 minutes per a session. Pre and post test results of the selected physical fitness variables were taken from both groups. Speed fitness was measured by using 60m (second) run test, power were tested by shot put (in meter), muscular endurance were tested by using chin up, muscular strength were measured by using sit-up test and flexibility were measured by sit and reach test. The data collected from the study subject was analyzed by using SPSS version 23 software. By using paired t-test from pre to post test results of the variables and the level of significance at 0.05. The result should showed physical fitness components such as speed (MD=0.621), power (MD= 0.492), ME (MD=2.778), MS (MD= 4.722) and flexibility (MD=1.111) were improved significantly followed in the 12 week resistance training in EG at (p<0.05). However CG has no significant change on the some selected physical fitness variables on post-test. Finally the researcher concluded that 12 week resistance training has a significant improvement on the some selected physical fitness variables, such as speed, power muscular endurance, muscular strength and flexibility. Keywords: Resistance training, muscular strength, muscular endurance, speed, power, flexibility, physical