Back ground and purpose of the study: The ability to perform selective trunk movements is important predictor of functional outcome in post stroke individuals. However, studies evaluating effect of trunk strengthening aimed at improving trunk performance and functional outcome is sparse. Objective of the study: To find out the effect of trunk strengthening exercise in improving trunk performance and functional outcome Study design: Randomized control trial Participants: Both male and female subjects with post stroke duration of 3 months to 1 year between the age group 50 to 60 years who attended rehabilitation centre and home physiotherapy. Intervention: A randomized controlled trial was carried out .Patients were randomized to receive either trunk strengthening or no trunk strengthening exercises. The 24 subjects were assigned to experimental group and control groups. Experimental group n=12 and control group n=12. The source of resistance exercise is body weight or partial bodyweight, As the exercise performance increases, progression of the exercise was done by increasing the leverage for the movement task.10 minutes of warm up, 25 minutes of exercise, 10 minutes of cool down for 14 days over a period of 4 weeks and 3 sets with 8 to 10 repetition was given. The subject will receive 3 set of each exercise in one session for 3 days per week for about 6 weeks of strength training. Rest period between the sessions was 1 to 2 minutes. Each of the 5 exercises given below is repeated for 8 to 10 times per set. This repetition is based on the ability of the subject to perform number of repetition at a stretch without fatigue. Trunk performances was evaluated by Trunk Impairment Scale (TIS) pre intervention and post intervention, Functional Independence Measure (FIM) motor sub total score to evaluate the functional outcome pre and post intervention. Results: Mann Whitney Test (U test) and Wilcoxon signed rank test was performed to know pre and post intervention effects. The mean age group for experimental group was 57.08±2.8 and mean age group for control group was 56.66±3.1. The mean duration of the patients after stroke in experimental group was 7.4±2.2 and control group 5.6±2.5. Gender distribution was equivalent between the groups. Within the experimental group there was significant improvement only in TIS score pre and post with p <0.007 when compared to within control group the TIS pre post was significant with p=0.027. The statistical analysis between the groups showed that there was no effect of trunk strengthening exercise in trunk performance (p=0.755) and functional outcome after strength training (p=0.713). Conclusion: The main aim of the study was to find the effect of trunk strengthening exercise and no trunk strengthening exercise in post stroke subjects. The result stated that there is no effect of trunk strengthening in functional outcome but there was significant improvement in trunk performance in experimental group. The conventional treatment in control group also showed no significant change in the treatment but had significant improvement in trunk performance. Though the trunk performance improved in both the groups comparison between groups showed no significant difference in functional outcome and trunk performance. Hence the set of exercise given in the study may not have served the purpose and a better set of exercise has to be used to perform the exercise.