Objectives: To study correlation between International Prostate Symptom Score (IPSS), maximum flow rate (Q-max), Prostate Volume (PV), Post Void Residual Urine (PVR) and Resistive Index (RI) and to evaluate changes in these parameters in cases of benign prostatic hyperplasia (BPH) pre and post treatment. Methods: The study was conducted on 30 cases of BPH. Parameters studied were IPSS, Q-max, PVR, PV and RI. 22 patients were subjected to medical therapy [Group I] and 8 to transurethral resection of prostate (TURP) [Group II]. They were reassessed at 6-weeks and 6-months post treatment. Statistical Analysis: Pearson’s coefficient of correlation was used for statistical analysis. Results: The mean age was 58.2 years (range 50–65). The mean pre-treatment IPSS of Groups I and II were 23.09±6.07 and 23.50±9.98 and prostate volumes were 48.90±12.42 ml and 37.75±9.5 ml respectively. Post-therapy, IPSS became 19.9±6.1 at 6-weeks and 14.18±5.8 at 6- months in Group I and 7.0±1.15 at 6-weeks and 4.5±1.0 at 6-months in Group II. In Group I, RI reduced from 0.75±0.05 to 0.69±0.03 at 6-weeks and to 0.62±0.04 at 6- months. In Group II, the RI reduced from 0.72± 0.06 to 0.59± 0.09 at 6-weeks and to 57±0.09 at 6-months. Conclusions: RI was significantly high in cases with moderate to severe symptoms that significantly reduced after treatment. It may become a non-invasive index for measuring bladder outlet obstruction in cases of BPH and may also serve as a prognostic marker.