The binding of peanut (PNA) and wheat germ (WGA) lectins to tissue sections was examined in biopsy specimens from normal urothelium (ten patients) and from tumor tissue of noninvasive (17 patients) and invasive bladder (31 patients) carcinomas. The results were correlated to DNA content, histopathologic grade, and the presence or absence of invasion. Significant alterations in lectin binding associated with the development of cancer were found. A gradual loss of both PNA and WGA binding was found to correlate with higher grades of atypia (P less than 0.001). The loss of WGA binding was significantly correlated with both tumor aneuploidy (P less than 0.001) and the presence of invasion (P less than 0.05), whereas no significant correlation was found between loss of PNA binding and these variables. We concluded that the loss of WGA binding structures associated with bladder cancer shows a better correlation with known risk factors (aneuploidy and invasion) than the loss of PNA binding does.