We examined immunohistochemically the expression of E-cadherin which is Ca2+ dependent intercellular adhesion molecules in bladder carcinoma and investigated the correlation among the expression of E-cadherin, pathological examination, clinical findings and course. Fifty cases of bladder carcinoma were examined except one squamous cell carcinoma. The pattern of the immunohistochemical staining by E-cadherin antibody were classified into 4 groups as follows. The tumor, over 75% of which cells were stained like normal epithelium, was regarded as (2+). When from 50% to 75% of the carcinoma cells were stained, it was (+). When from 25% to 50% of the carcinoma cells were stained, it was (+/-). The tumor showing that under 25% of the cells were stained or lack of staining was regarded as (-). It was demonstrated that the percentage of positive staining was significantly lower in cases of high grade or high stage tumors compared with those of low grade or low stage. As the pattern of invasion, 88% of the cases showing INF alpha was observed as (2+) or (+), while all cases with INF gamma showed (+/-) or (-). The patients with superficial tumors showing (+/-) or (-) tended to have the higher local recurrence rate of the carcinoma compared with those showing (2+) or (+) staining. Immunoblotting analysis demonstrated no evidence of gross alteration of E-cadherin molecules between normal and carcinoma cells of the bladder. In conclusion, the decrease of E-cadherin expression may contribute to the tumor grade and invasiveness of bladder carcinoma.