Objective: This study aimed to investigate whether body mass index (BMI) is correlates to severity of prostate. Materials and Methods: Medical records of 50 Iraqi patients who visited the Imam Hussain Center for Oncological and Hematological Diseases Directorate were collected during the period extending between (November 2021 to April 2022), their age were ranged from 51 to 80 years. Results and Discussion: In this study has been observed the relationship between BMI and the severity of prostate cancer based on Gleason scores was a weak positive (when BMI increased, Gleason scores also increased) weak significant correlation between BMI and the severity of prostate cancer based on Gleason scores, and these results revealed of the higher the Gleason scores, the higher of the BMI of prostate cancer patients in this study. Conclusion: Prostate cancer patients' BMI had a weakly positive correlation with their Gleason score.