The aim of the study was to find out the correlation between white blood cell (WBC) counts in semen and quantitative composition of seminal microflora, and to establish the minimum WBC count associated with significant bacteriospermia. The research included 159 men with different WBC counts in their semen, 84 of them with chronic prostatitis/chronic pelvic pain syndrome. Semen samples were cultivated quantitatively for detecting anaerobic, microaerophilic and aerobic bacteria. Bryan-Leishman stained slides were used for detecting WBC in semen. Seminal fluid was colonized by eight different microorganisms, and the total count of microorganisms in semen ranged from 102 to 107 CFU ml-1. A high frequency of anaerobic microorganisms was found. A positive correlation was observed between the WBC count and the number of different microorganisms, and also between the WBC count and the total count of microorganisms in semen sample. The receiver operating characteristic curve analysis demonstrated that the WHO-defined WBC cut-off point (1 x 106 WBC ml-1) has very low sensitivity for discriminating between patients with and without significant bacteriospermia, as a more optimal sensitivity/specificity ratio appears at 0.2 x 106 WBC ml-1 of semen. The quantitative microbiological finding of semen in the patients of National Institute of Health (NIH) categories IIIa and IV was very similar, i.e. a high number of different microorganisms and a high total count of microorganisms. In the control group (without leucocytospermia and prostatitis symptoms) both parameters were significantly lower.