Aim:The aim of this study was to investigate the relationship between obesity and lower urinary tract symptoms and prostate volume in patients who underwent prostate biopsies.Materials and Methods:Between December 2008 and November 2009, transrectal ultrasound-guided prostate biopsy was performed on patients who had elevated prostate-specific antigen levels or abnormal digital rectal examination findings. A total of 211 patients were included in this study. Prostate volumes, International Prostate Symptom Score (IPSS) values, and the patient's height and weight were all recorded during the biopsy. Body mass index (BMI) <18.5 was determined as underweight, 18.5–23.0 normal, 23.0–27.5 overweight, and >27.5 obese.Results:The mean age of the patients was 68.0 ± 6.3 years, and the mean BMI was 28.0 ± 4.9 kg/m2. The mean prostate volume of the normal, overweight, and obese groups was 30, 50, and 70 ml, respectively. The positive and statistically significant correlation between BMI and prostate volume was determined (P < 0.001). According to BMI, the mean IPSS was 8.0, 16.5, and 20.0 in the groups, respectively. Similarly, a statistically positive correlation between BMI and IPSS was demonstrated (P < 0.001).Conclusions:As the result of a rise in BMI, prostate volumes and IPSS increase in patients. Prostate volume and IPSS decrease due to weight loss, and hence that fewer urinary symptoms occur, and the quality-of-life of patients may increase.