['We examine whether leukocytes and bacteria correlate with symptom severity in men with chronic prostatitis/chronic pelvic pain syndrome.', 'All 488 men screened into the National Institutes of Health Chronic Prostatitis Cohort Study before close of recruitment on August 22, 2001 were selected for analysis. The National Institutes of Health Chronic Prostatitis Symptom Index, including subscores, were used to measure symptoms. Urethral inflammation was defined as white blood cell (WBC) counts of 1 or more (1+) in the first voided urine. Participants were classified as category IIIa based on WBC counts of 5 or more, or 10 or more (5+, 10+) in the expressed prostatic secretion, or 1+ or 5+ either in the post-expressed prostatic secretion urine (voided urine 3) or semen. Uropathogens were classified as localizing if the designated bacterial species were absent in voided urine 1 and voided urine 2 but present in expressed prostatic secretion, voided urine 3 or semen, or present in expressed prostatic secretion, voided urine 3 or semen at 2 log concentrations higher than at voided urine 1 or 2. Associations between symptoms, and inflammation and infection were investigated using generalized Mantel-Haenszel methods.', 'Of all participants 50% had urethral leukocytes and of 397 with expressed prostatic secretion samples 194 (49%) and 122 (31%) had 5+ or 10+ WBCs in expressed prostatic secretion, respectively. The prevalence of category IIIa ranged from 90% to 54%, depending on the composite set of cut points. None of the index measures were statistically different (p >0.10) for selected leukocytosis subgroups. Based on prostate and semen cultures, 37 of 488 men (8%) had at least 1 localizing uropathogen. None of the index measures were statistically different (p >0.10) for selected bacterial culture subgroups.'] Do leukocyte and bacterial counts correlate with severity of symptoms in men with chronic prostatitis : the National Institutes of Health Chronic Prostatitis Cohort Study?