© 2014 The Authors BJU International © 2014 BJU International. Objective: To examine whether or not the combination of diclofenac suppository with peri-prostatic nerve block (PPNB) was effective in reducing the degree of pain experienced during transrectal ultrasound (TRUS)-guided prostate biopsy in a randomised single-blind placebo-controlled trial. Patients and Methods: In all, 96 patients having a planned TRUS-guided prostate biopsy were randomised into one of the following arms on a 1:1 basis: 10 mL 1% lignocaine PPNB and placebo suppository (control) or 10 mL 1% lignocaine PPNB and 100 mg diclofenac suppository (treatment). Pain scores were recorded using the Numerical Rating Scale for pain (0-10) at the following time-points: (i) introduction of probe, (ii) during biopsy, (iii) 1 h after biopsy, (iv) later that evening (≈6 h after biopsy) and (v) 1 day after biopsy. Patients were asked about their preferred method for pain control if a repeat TRUS-guided prostate biopsy was required: local anaesthetic (LA) again or intravenous sedation. Results: There were no significant differences in age (P = 0.653) or PSA level (P = 0.584) between either study arm. The differences in pain scores between the control and treatment groups were not significant at Time 1 (probe insertion; P = 0.299), Time 2 (biopsy; P = 0.983), Time 4 (evening after; P = 0.231) and Time 5 (1 day after biopsy; P = 0.384). At Time 3 (1 h after biopsy), the control pain scale scores were statistically significantly higher than the treatment pain scale scores (P = 0.044). There was no difference between treatment (87%) and control (80%) groups as to whether they would prefer to repeat the biopsy under LA (P = 0.373). Conclusion: The use of a diclofenac suppository with PPNB did not show any clinically meaningful effect in decreasing pain or improving tolerability of TRUS-guided prostate biopsy and is not recommended. PPNB TRUS-guided biopsy is extremely well tolerated, with >80% of patients electing for subsequent LA biopsy if required.