This chapter, ‘Prostatitis or chronic pelvic pain syndrome in men’, provides the reader with a comprehensive overview of these syndromes. There are separate sections for acute bacterial prostatitis, chronic bacterial prostatitis, and chronic prostatitis/chronic pelvic pain syndrome (CPPS). The Chronic Prostatitis Symptom Index (from National Institutes of Health) is included as a potentially useful tool in the assessment of men presenting with CPPS. Rarer causes of prostatitis are also outlined including granulomatous prostatitis (TB), parasites, viruses, and mycoses. The potential role of sexually transmitted pathogens is also included. HIV is mentioned as a risk for abscess formation in men presenting with bacterial prostatitis.