Abstract A total of 1442 patients with symptoms of chronic prostatitis were examined over a 4-year period at the Outpatient Department for Urogenital Infections, University Hospital for Infectious Diseases “Dr. Fran Mihaljevic”, Zagreb, Croatia. An infectious aetiology was determined in 1070 (74.2%) patients. In 561 of 1070 (52.4%) patients the inflammatory finding (>10 WBC/hpf) was found in expressed prostatic secretions (EPS) or voided bladder urine (VB 3). Normal, <10 WBCs/hpf was found in 362 of 536 (67.5%) patients with symptoms of chronic prostatitis in whom Chlamydia trachomatis was detected in EPS or VB 3, in 51 of 151 (33.8%) patients with isolated Trichomonas vaginalis and in 40 of 72 (55.6%) patients with isolated Ureaplasma urealyticum. Escherichia coli was the causative pathogen in 95, Enterococcus in 68, Proteus mirabilis in 37, Klebsiella pneumoniae in 16, Streptococcus agalactiae in 19, and Pseudomonas aeruginosa in 3 patients with chronic prostatitis. Other patients had a mixed infection. In patients with chronic bacterial prostatitis (CBP) caused by E. coli, P. mirabilis, K. pneumoniae, E. or S. agalactiae, an inflammatory finding was regularly found in EPS or VB 3.