This prospective study on men undergoing transrectal ultrasonography (TRUS) biopsies was performed to evaluate the prevalence and to classify prostatic calcification (PCalc) on TRUS and correlate the findings with histology. Images of the prostate were saved at three defined regions: (1) at maximum prostate transverse diameter; (2) at maximum prostate sagittal diameter; and (3) transverse and sagittal points where the calcification under evaluation was most accurately defined. These images were printed and blindly analysed by an experienced urologist. Calcification was classified according to zonal distribution into transitional, interface, and peripheral, as well as unilateral or bilateral, which the authors have described as the Collins Classification. These were correlated with histological data. Out of 476 patients studied, 274 patients (58.8%) had prostate cancer, 88 patients (18.9%) inflammation, and 104 patients (22.3%) had benign pathology. Interface calcification was present in 42.3% of patients. Peripheral or transitional zone calcification was unusual (6.8% and 9.0%, respectively). Of the peripheral zone calcification group patients, 78.1% had cancer on histology examination. There was no statistical association between PCalc subtypes and CaP Gleason grade, lower urinary tract symptoms (LUTS), prostatitis symptoms or prostate specific antigen (PSA) levels. The authors conclude that interface calcification is common and not associated with any particular pathology and peripheral zone calcification appears to be strongly associated with prostate cancer.