C-erbB-2 gene amplification and protein overexpression have been implicated as prognostic markers for patients with recurrent progressive bladder tumors. This event has been investigated as a potential diagnostic indicator in archival samples of transitional cell carcinoma of the bladder. Two hundred thirty-six bladder tumors from 89 patients with recurrent disease (mean follow-up, 4 years), 20 tumors from patients with no evidence of bladder tumor recurrence (mean follow-up, 7 years) and 10 normal bladder controls (patients with no history of transitional cell carcinoma) were studied. A differential PCR was used to provide a semiquantitative estimate of C-erbB-2 gene amplification. Protein overexpression was assessed immunohistochemically. Sixteen of 89 patients with recurrent disease had evidence of C-erbB-2 gene amplification. No C-erbB-2 gene amplification was seen in the nonrecurrent tumors or normal bladder controls. Of the 89 patients with recurrent bladder tumors, 43 had evidence of progressive disease, and of these, 14 patients exhibited C-erbB-2 gene amplification, indicating a strong association with gene amplification and progressive disease (P < 0.0005). Gene amplification in these patients was seen only after disease progression had occurred. Protein overexpression was seen in 50% of patients with recurrent and 45% of patients with nonrecurrent disease. No protein overexpression was seen in normal controls. Protein overexpression could not be linked to disease progression. C-erbB-2 gene amplification and protein overexpression were of predictive value in multivariate analysis for overall bladder cancer death; however stage and grade remained the most important independent prognostic variables. C-erbB-2 gene amplification and protein overexpression were of no value as independent markers for the prediction of disease recurrence or progression. It appears from these results that the role of C-erbB-2 as a diagnostic marker may far outweigh its usefulness as a prognostic indicator.