Immunizing mice with a transitional cell cancer (TCC) tissue in the renal pelvis, we produced a monoclonal antibody (EH14) against new epithelial antigens. After the mice were immunized repeatedly, their splenic cells were harvested and fused with NS/1 myeloma cells. The normal kidney tissue of the same patient was used on Dot blots to select the hybridoma. A a result, one hybridoma whose antibody (EH14) reacted very strongly with TCC but only faintly with normal kidney tissue or normal bladder mucosa was obtained. On immunohistochemistry, EH14 stained all of the 29 TCC tissues. EH14 also stained uterus cancer (7/7) and gastric cancer (6/6) as well as the normal squamous cell and many types of the normal epithelium. All of the lymphnodes containing metastatic bladder cancer were strongly stained with EH14. EH14, however, did not stain interstitial tissues, muscles and sarcomas. The molecular weight of the antigen recognized by EH14 was 14KD and 28 KD on Western blot analysis, and the antigen was stable with formalin or ethanol. The antigen was not the same as that reported previously, and may be useful as a histological marker of TCC.