Cell surface adhesion molecules, E-cadherin and exon v6 containing CD44 isoforms (CD44v6), were readily found in well-to-moderately differentiated urothelial cell lines but were down-regulated in poorly differentiated cell lines. One hundred and fifteen tumors of transitional cell carcinoma (TCC) were examined with E-cadherin and CD44v6 specific antibodies. Sixty-five (56.5%) tumors exhibited a preserved type while 50 (43.5%) showed a reduced type for CD44v6. Sixty-seven (58.3%) tumors were classified as the preserved type, and 48 (41.7%) were classified as the reduced type for E-cadherin. The staining pattern of E-cadherin was the same as that of CD44v6 in 87.0% (100 of 115) of tumors. The frequency of the reduced type was higher in poorly differentiated carcinomas (32 of 52 for CD44v6, p = 0.001; 27 of 52 for E-cadherin, p = 0.112) and tumors with an invasive growth pattern (22 of 27 for CD44v6, p < 0.001; 20 of 27 for E-cadherin, p < 0.001) than it was in well-differentiated carcinomas and tumors with expansile growth. However, the association with lymph node involvement or distant metastasis did not reach statistical significance. There was no difference in survival in reference to the expression patterns of CD44v6 and E-cadherin. Furthermore, neither marker was a significant prognostic factor for tumor recurrence and survival according to Cox's multiple variant regression analysis.