The serum concentrations of prostatic secretory protein of 94 amino acid residues (PSP94) as well as those of prostate-specific antigen (PSA) were determined in 40 patients with established prostatic carcinoma, prior to transurethral resection of the prostate. In a comparison with a control group of healthy men (n = 40) and a group of patients with histologically established benign prostatic hyperplasia (n = 40) no significant differences in PSP94 serum concentrations between the groups were observed. Similarly, correlations of PSP94 serum concentrations with prostatic carcinoma stages or grades were not detected. In contrast, and as expected, PSA behaved as a prostate tumor marker of known sensitivity and specificity. A correlation of PSP94 and PSA concentrations in sera of patients with benign prostatic hyperplasia and/or prostatic carcinoma could not be verified. PSP94 apparently does not fulfill the criteria of a serum marker for monitoring adenomas and/or carcinomas of the prostate.