The clinical differential diagnosis of chronic prostatitis and psycho-vegetative urogenital syndrome with objective laboratory tests is very difficult. 265 ejaculates with possible chronic prostatitis were bacteriologically examined (including the search for STD agents). To verify an inflammatory process in the prostate and adnexae, we tested the C3 complement, coeruloplasmin and PMN-elastase levels in ejaculate. In addition, semiquantitative leucocyte counts in stained smears of the ejaculate were carried out. 185 of 265 patients had C3 complement below detection levels or in the normal range excluding inflammation of prostate or adnexae. 16.8% of the C3-negative ejaculates showed an elevated PMN-elastase level associated with urethritis anterior and/or posterior caused by STD agents. 80 patients showed elevated C3 levels; 38.8% with elevated coeruloplasmin and PMN-elastase levels. The semiquantitative leucocyte count in the stained smear proved the least sensitive method for verifying an inflammation. Enterococci (55.3%), Mycoplasma (18.8%) and Escherichia coli (16.5) were the dominant pathogens of chronic prostatitis present in number of 10(2) cfu/ml or > 10(5) cfu/ml. A correlation to the intensity of the inflammation was not found. These results show how important it is to realise a complete bacteriological examination as well as to determine the C3 complement, coeruloplasmin and PMN elastase.