Expression of c-erbB-2 protein, neuron-specific enolase (NSE) and DNA ploidy was studied by immunohistochemistry and flow cytometry in formalin-fixed and paraffin-embedded specimens from 104 patients with locally advanced transitional cell carcinoma of the bladder. Positive membrane bound c-erbB-2 staining was found in 15% of the tumours, and 38% of the tumours were positive for NSE. Only one tumour stained positively for both NSE and c-erbB-2. Expression of c-erbB-2 protein and NSE was neither correlated to tumour stage nor to histopathological grade. The frequency of non-diploid tumours was 78% in 49 c-erbB-2/NSE negative tumours, 98% in 40 NSE positive tumours, and 100% in 16 c-erbB-2 positive tumours (P = 0.004). Whether the c-erbB-2 expression is a useful prognostic marker in addition to other conventional parameters, remains to be shown.