Background: Sacral Index is the most important parameter in assessing the sexual dimorphism. Materials and Methods: A total of 42 dry adult human sacral bones of known sex (19 -female sacra; 23male sacra) collected from Anatomy Department, Santhiram Medical College, Nandyal. The sacral length measured from the promontory to the middle of antero-inferior margin of last sacral vertebra. The sacral breadth measured from the lateral most points of ale of sacrum. The sacral index (SI) is calculated and statistically analyzed. Results: We noted the mean sacral index 101.142+2.148 in male sacra, and 103.668+2.271 in female sacra with significantly higher sacral index in female sacra than male sacra in the present study. Conclusion:Our study acknowledges the importance of sacral index and its significance can be useful in sexual dimorphism.