Objectives. To investigate the efficacy of unilateral pudendal nerve block for the relief of all pain during transrectal ultrasound (TRUS)-guided prostate biopsy. TRUS-guided prostate biopsy is the standard procedure to diagnose or rule out prostate cancer. The pain, attributed to ultrasound probe insertion and the needle punctures into the prostate, inflicted by TRUS-guided prostate biopsy limits its effectiveness. Methods. We performed a prospective, randomized, double-blind, placebo-controlled study of 65 consecutive men suspected of having prostate cancer who were undergoing TRUS-guided prostate biopsy, 51 of whom fulfilled the inclusion criteria. Before the biopsy, each patient was randomized to one of two groups. Both the patient and the physician who performed the TRUS-guided biopsy were unaware of the contents of the injection for the pudendal nerve block. Unilateral pudendal nerve blockade was performed transperineally with digital rectal examination guidance using 10 mg of 1 % prilocaine (group 1 [n = 26]) or 10 mL of a 0.9 NaCl solution (group 2 [n = 25]) by way of a 22-gauge spinal needle by the same anesthetist. Pain was evaluated using an 11-point visual analog scale questionnaire. Results. No statistically significant differences were found in the visual analog scale score for pain during the pudendal nerve blockade or digital rectal examination between the groups. A statistically significant difference was found in the visual analog scale score for the biopsy procedure (P < 0.01) and probe discomfort (P < 0.05) between the two groups. Conclusions. Unilateral pudendal nerve blockade was effective in reducing the pain at both biopsy and probe manipulation in our study.