The cell kinetic fractions (G0/G1; S; G2 + M) were evaluated by DNA flow cytometry (DNA FCM) in 102 biopsies from bladder carcinoma, previously untreated by cytotoxic therapy, and in 25 biopsies taken at least 3 months after prior treatment (chemotherapy, radiotherapy, surgery). Non-diploid DNA-stemlines were most often found in tumours of a high T category and of a high histopathological grade. Also the number of tumours with a fraction of cells in S-phase above 10% correlated with the clinical stage and histological grade. When the cytotoxic treatment preceded the actual biopsy by 3 months or more the distribution of stemline ploidies in the recurrent or residual tumours were similar to that seen in previously untreated patients. Furthermore, 4 of 5 individual muscle infiltrating bladder tumours treated with surgery, radiotherapy or systemic chemotherapy had the same stemline ploidy before and after treatment. The analysis of ploidy and cell kinetic parameters obtained from DNA FCM offers a possibility to evaluate the prognosis and the therapy effects in human bladder carcinoma.