Background: Benign Prostatic Enlargement {BPE} is a common urological condition in the aging male that causes infra-vesical obstruction. This obstruction subsequently leads to PVR and bladder wall hypertrophy. The objective diagnosis of BOO is through urodynamic studies. However, ultrasonography, a non-invasive procedure can also be an effective method in assessing BOO. IPSS, BWT, uroflowmetry and PVR constitute the non-invasive determinants of BOO. If prostate volume correlates with these parameters, possible outcomes of further investigations and management can be predicted thereby reducing delay in appropriate choice of treatment. Objective: This study was aimed at determining the correlation between prostate volume and bladder outlet obstruction in men with Benign Prostatic Enlargement. Methodology: This was a hospital based cross-sectional prospective study of newly diagnosed patients with BPE. Following ethical approval from the Lagos University Teaching Hospital ethical committee, 100 patients who met the inclusion criteria were enrolled. The severity of LUTS was documented using the IPSS. The prostate volume, bladder wall thickness and post void residual volume were measured via transabdominal ultrasound using Toshiba Nemino XG {Osaka Japan} with probe frequency 3.5MHz. Basic uroflowmetry was carried out using Urodyn 1000 plus uroflowmeter. Data were collected into a proforma and were analysed using SPSS version 22 {IBM, SPSS, Chicago, IL, USA}. P value < 0.05 was considered to be statistically significant. Results: The age range of the study population was 46 to 85 years while the mean age was 62.87±8.69 years. The mean total IPSS was 17.91±7.11. The majority of the patients had IPSS of 8-19. The prostate volume ranged from 21.8 to 312.9mls with a mean 77.75±53.21mls. The mean bladder wall thickness was 4.44±1.6mm. The highest BWT of 10mm was seen in a 48year old man with a prostate volume of 65mls. The mean post void residual volume was 40.63±43.88. The mean peak flow rate was 11.67±6.45mls/s while the minimum Qmax of 2.1mls/s was measured in a 64year old man with a prostate size of 101.7mls. There was a weak positive correlation between the prostate volume and total IPSS {r=0.092; p=0.361} and between prostate volume and post void residual volume {r=0.118; p=0.242} in men with BPE. These were not statistically significant. However, there was a weak but statistically significant positive correlation between the prostate volume and BWT {r=0.231; p=0.021}. There was a weak negative correlation between the prostate volume and maximum flow rate {r=-0.137; p=0.174}. This was also not statistically significant. Conclusion: There was a weak positive correlation between prostate volume and BOO. There was a weak positive correlation between prostate volume measured by transabdominal ultrasound and symptoms severity scores and post void residual urine volume. There was a weak negative correlation between PV and peak flow rate. All these were not statistically significant. This may be as a result of the small sample size. However, there was a weak but statistically significant correlation between PV and bladder wall thickness. Larger sample size may be able to achieve statistical significance. Keywords: Benign Prostatic Hyperplasia, prostate volume, International Prostate Symptoms Score, Post void residual, Bladder Wall Thickness, Peak flow rate.