OBJECTIVES. The aim of the study was to explore possible production of prostate-specific markers by the embryologically and physiologically related accessory male sex glands, other than the prostate. METHODS. The accessory male sex glands of Cowper, Littre, and Morgagni were studied systematically in 10 whole-mount autopsy and 5 surgical cystoprostatourethrectomy specimens. Immunohistochemistry was applied with the avidin-biotin-peroxidase method and commercially available monoclonal antibodies raised against prostate-specific antigen (PSA) and prostate-specific acid phosphatase (PSAP). RESULTS. All specimens showed clear microscopic identification of these glands except for Cowper's glands, which were not found in most of the surgical cystoprostatourethrectomy specimens but were found coincidentally in one. Localization of the prostate-specific markers PSA and PSAP was demonstrated for the first time in three Cowper's glands, but they were a consistent finding in Littre's and Morgagni's glands when immunohistochemical identification was performed in a systematic fashion. CONCLUSIONS. PSA and PSAP are mostly produced by prostatic tissue, but not exclusively. These findings may have an impact on the specificity and sensitivity of PSA serum levels after radical prostatectomy because they support the hypothesis of extraprostatic sources of PSA.