The study was designed to investigate the effect of core strength training on selected physical variables of inter-school boy’s handball players. To investigate the study, thirty inter-school boys handball players were randomly selected from NS handball academy Coimbatore and their age were ranged between 14 and 17 years. The subjects were randomly assigned to two equal groups (n=15). All the subjects were divided in to two groups with 15 subjects each as experimental and control group. Group-I underwent core strength training for a period of twelve weeks and group-II acted as control who did not participate in any special training other than the regular routine. The physical fitnessvariables such as shoulder strength and leg explosive power were selected as dependent variables. Pre and post-test random group design was used for this study. The dependent‘t’test was applied to determine the difference between the means of two groups. To find out whether there was any significant difference between the experimental and control groups. To test the level of significant of difference between the means 0.05level of confidence was fixed. The result of the study shows that, there was a significant changes takes place on shoulder strength and leg explosive power of inter-school boys handball playersdue to the effect of twelve weeks of core strength training. And also concluded that, there was a significant difference exists between experimental and control groups in shoulder strength and leg explosive power. The control group did not significant changes the selected criterion variables.