Benign prostatic hyperplasia (BPH) is a nonmalignant pathological enlargement of the prostate, which occurs primarily in the transitional zone. BPH is highly prevalent and is a major cause of lower urinary tract symptoms in aging males, although there is no direct relationship between prostate volume and symptom severity. The progression of BPH can be quantified by measuring the volumes of the whole prostate and its zones, based on image segmentation on magnetic resonance imaging. Prostate volume determination via segmentation is a useful measure for patients undergoing therapy for BPH. However, prostate segmentation is not widely used due to the excessive time required for even experts to manually map the margins of the prostate. Here, we review and compare new methods of prostate volume segmentation using both manual and automated methods, including the ellipsoid formula, manual planimetry, and semiautomated and fully automated segmentation approaches. We highlight the utility of prostate segmentation in the clinical context of assessing BPH.