Introduction: Benign prostate hyperplasia, pathophysiology contributes to bladder outlet obstruction due to functional obstruction caused by gland size enlargement resulting in the lower urinary tract symptoms (LUTS). Objectives: To determine the correlation of the prostate volume with surgical outcomes and postoperative LUTS in patients with benign prostatic hyperplasia (BPH) undergoing transurethral resection of the prostate (TURP). Patients and Methods: Patients with BPH who were refractory for medical treatment enrolled in the study. Patients divided into three groups with attention to their prostate volume conducted by transabdominal ultrasonography. To evaluate patients' LUTS, the International Prostate Symptom Score (IPSS) questionnaire was filled for all patients preoperatively and during the first and third months follow up sessions.Results: In the current study, mean age of the patients was 66.92 ± 1.08 years. Of 111 patients, eight patients (7.2%) had prostate volume less than 30 cc, 59 patients (53.2%) had prostate volume between 30-60 cc, and 44 patients (39.6%) had prostate volume more than 60 cc. During first month postoperative, mean decrease in IPSS scores in patients with prostate volume less than 30 cc, prostate volume between 30-60 cc and prostate volume more than 30 cc were 27.72 ± 3.53, 27.32 ± 3.37 and 27.45 ± 2.87, respectively. The ANOVA test showed no significant difference between the groups (P= 0.93). Mean decrease in IPSS score during third month postoperative, had no significant difference between the three groups, too (P=0.71). Symptoms alleviation observed in 94.6% and 95.5% of the patients, during first and third months follow-up, respectively. Conclusion: There was no correlation between the IPSS scores decrease and patients' symptoms recovery and preoperative prostate volume in patients with BPH who underwent TRUP. ABSTRACTImplication for health policy/practice/research/medical education: IPSS scores cannot predict the patients' symptoms recovery and preoperative prostate volume in patients following TRUP. Please cite this paper as: Lotfi B, Farazhi S, Mohammadi Fallah M, Alizadeh M, Valizadeh R, Mohammad Rahimi S. Effect of preoperative prostate volume on the improvement of lower urinary tract symptoms in patients with benign prostatic hyperplasia undergoing transurethral resection of prostate. J Nephropathol. 2020;9(2):e18.