Purpose We compared prostate cancer detection rates achieved using an 8 and 12-core biopsy protocol in a clinical population to determine the significance of additional transition zone sampling on repeat biopsy. Materials and Methods Between September 2004 and September 2007, 269 eligible patients with a clinical suspicion of prostate cancer referred to our department were randomized to an 8-core lateral (group 1) or a 12-core lateral and parasagittal (group 2) transrectal ultrasound guided prostate biopsy protocol. Study inclusion criteria were age dependent increased serum prostate specific antigen (1.25 ng/ml or greater at ages less than 50 years, 1.75 or greater at ages 50 to less than 60 years, 2.25 or greater at ages 60 to less than 70 years and 3.25 or greater at ages 70 years or greater), positive digital rectal examination and/or suspicious transrectal ultrasound. After negative first round biopsy patients underwent 12-core biopsy, including 4 transition zone cores. Results Nine patients were excluded from analysis because of protocol violation or they did not complete the whole biopsy procedure due to discomfort. The cancer detection rate in groups 1 and 2 did not differ significantly (34.1% or 45 of 132 patients and 38.3% or 49 of 128, respectively, p = 0.48). Detected cancer median Gleason scores were similar in the groups. Of 109 patients who underwent repeat biopsy prostate cancer was detected in 20 (14.4%), of whom 9 had positive cores from the transition zone and 6 had positive biopsies only from the transition zone. Conclusions There are no statistically significant differences in the prostate cancer detection rate between 8 and 12-core prostate biopsy protocols. Transition zone biopsies contribute to prostate cancer detection in a repeat biopsy protocol.