Background & Purpose: Variations in the application of muscle energy technique (MET) for increasing the extensibility of muscles have been advocated, but little evidence exists to support the relative merit of a particular approach. This study investigated two types of muscle energy techniques that have been advocated in the osteopathic literature that differ primarily in the muscle group targeted. Aim: To compare the efficacy of Post Isometric Relaxation (PIR) and Reciprocal Inhibition (RI) on hamstring length in young healthy adults Methodology: Randomized clinical trial 100 college students aged between 18-25 years were included. The subjects were randomly assigned to PIR and RI group. Each group consisted of 50 subjects (25 male, 25 female). Knee extension limitation was measured by using active knee extension test (AKET) pre & post-intervention, i.e. after 3 weeks of stretching regimen, with the help of universal full circle goniometer. Results: There was significant improvement in hamstrings flexibility (p=0.000) in both PIR and RI groups. Statistical comparison of the results of both the technique showed that PIR group had greater improvement than the RI group (p=0.000) Conclusion: PIR and RI were both found to be effective in improving hamstring flexibility but, PIR is more effective therapeutic maneuver.