In a case histologically proven prostatic ductal adenocarcinoma with endometrioid features associated with rectal invasion and multiple liver metastases the expression of prostate specific antigen (PSA) and carcinoembryonic antigen (CEA) was studied immunohistochemically on paraffin sections to clarify markedly elevated PSA and relatively elevated CEA in sera. All of prostatic ductal adenocarcinoma with endometrioid features, rectal invasion and liver metastases gave positive staining for PSA. Although rectal invasion and liver metastases gave positive staining for CEA, the primary tumor was never stained for CEA. Further study is necessary to clarify any significance of CEA within the cancer cell.