Fifty-five patients with muscle-invasive transitional cell carcinoma of the bladder were treated with preoperative cisplatin-based chemotherapy followed by radiotherapy (20 Gy within 1 week) and cystectomy. DNA flow cytometry (FCM) was performed in paraffin-embedded tissue obtained by transurethral resection immediately before therapy. Together with the T-category and histological grade, DNA ploidy and S-phase fraction (SPF) were evaluated for the ability to predict the response to chemotherapy/radiotherapy and survival: a low T-category, but neither DNA ploidy nor SPF, was predictive for the response to neo-adjuvant treatment. The T-category was not related to the patients' survival. In the Cox regression analysis, SPF was an independent prognostic parameter together with response to the precystectomy therapy. We concluded that, in spite of remaining technical problems, paraffin-embedded tissue from bladder carcinoma is suitable for DNA FCM. Contrary to the situation in superficial bladder cancer, DNA ploidy is not related to the clinical outcome in muscle-invasive bladder carcinoma treated by neo-adjuvant chemo-/radiotherapy and cystectomy. SPF seems to be a clinically worthwhile parameter with significance that has to be further studied in larger series.