STUDY TYPE: Prognosis (cohort). LEVEL OF EVIDENCE: 2a. OBJECTIVE: To provide a summary, using the National Institutes of Health Chronic Prostatitis Symptoms Index (NIH-CPSI), of the prevalence of prostatitis-like symptoms in a population-based sample of Australian men. SUBJECTS AND METHODS: Participants were Australian men aged 16-64 years recruited as part of the Australian Longitudinal Study of Health and Relationships: a nationally representative study. In all, 1346 men completed an extensive questionnaire which included the NIH-CPSI. The index identifies six types of urogenital pain, the presence of urinary problems, and effects on quality of life. Men who reported perineal and/or ejaculatory pain or discomfort and a total NIH-CPSI pain score of > or =4 were considered as having prostatitis-like symptoms. RESULTS: Based on a weighted population of 1373 men, some form of urogenital pain was reported by 105 (7.6%) men; with 2.8% of men reporting more than one type of urogenital pain. The mean (range) NIH-CPSI pain score for men reporting pain was 6.2 (5.6-6.8); for all men the mean score was 0.5 (0.4-0.6). About 20% of men (284) were considered to have urinary problems. The mean urinary symptom score for all men was 0.9 (0.9-1.0). The mean total NIH-CPSI score for men reporting pain was 13.3 (12.0-14.7) and for all men it was 2.6 (2.3-2.8). The estimated prevalence of prostatitis-like symptoms was approximately 2%. CONCLUSIONS: Using the NIH-CPSI the estimated prevalence for urogenital pain in Australian men is 8%; an estimated 3% of men experience pain from more than one urogenital location. The estimated prevalence of prostatitis-like symptoms in Australian men is 2%. Almost a third of Australian men experiencing urogenital pain or prostatitis-like symptoms would be less than satisfied if this was to be ongoing for the rest of their life.