OBJECTIVES Nocturia is a well-recognized symptom of benign prostatic hyperplasia (BPH), which is commonly treated by alpha(1)-blockers and/or 5 alpha-reductase inhibitors. However, the effectiveness of these drugs for nocturia has been reported to be only 25%-39%. The aim of this Study was to investigate the efficacy of celecoxib, a cyclooxygenase-2 inhibitor, in the treatment of patients with BPH complaining of nocturia. METHODS This was a prospective, randomized, double-blind, placebo-controlled study. A total of 80 men with lower urinary tract symptoms and BPH were entered into the Study and were randomized to receive celecoxib, 100 mg at 9 Pm vs placebo for I month. The inclusion criteria also included a total International Prostate Symptom Score >8 and complaints of >= 2 voids nightly. The efficacy and safety of the treatment were assessed by changes in the urinary flow and symptoms between baseline and I month of follow-up. RESULTS In the celecoxib group (n = 40), the mean nocturnal frequency (+/- SD) decreased from 5.17 +/- 2.1 to 2.5 +/- 1.9 (P < .0001), and the mean International Prostate Symptom Score (+/- SD) decreased from 18.2 +/- 3.4 to 15.5 +/- 4.2 (P < .0001). In the control group (n = 40), the mean nocturnal frequency (+/- SD) decreased from 5.30 +/- 2.4 to 5.12 +/- 1.9 (P > .05), and the mean International Prostate Symptom Score (+/- SD) decreased from 18.4 +/- 3.1 to 18 +/- 3.9 (P > .05). A statistically significant difference was found between the 2 groups (P < .0001). No statistically significant differences were found in the changes in the peak flow rate between the celecoxib and control groups or in celecoxib group between baseline and I month (P > .05). No significant side effects were reported. CONCLUSIONS Celecoxib is effective in the treatment of patients with BPH complaining of refractory nocturia. Our results suggest a novel treatment option for this common condition.