In order to define the prognosis of pure squamous carcinomas of the bladder, on the one hand (group I), and the possible aggravating role of the presence of squamous tissue in an invasive renal cell tumour, on the other hand (group II), 46 cases files of patients treated between 1975 and 1984 were analysed retrospectively. Group I consisted of 18 cases of pure squamous carcinoma (11 men with a mean age of 71 years and 7 women with a mean age of 74 years). 66% of cases presented with haematuria, but urinary cytology was of little help. The diagnosis was established by transurethral resection with 18 grade 3 tumours: stage A in 4 cases and stage B in 14 cases. 10 patients had unilateral (8 cases) or bilateral (2 cases) complications of the upper urinary tract. The presence of lymph node and/or haematogenous metastases was investigated by bone scan, hepatic ultrasonography, pulmonary tomography and, most importantly, by bipedal lymphography combined with percutaneous cyto-aspiration of suspicious nodes. 4 patients presented with invasion of the obturator lymph nodes (2 cases) and iliac lymph nodes (2 cases). 9 patients were treated by total cysto-prostatectomy, 6 patients by radiotherapy (60 Grays) and 3 patients did not receive any treatment. The overall survival was 12.5% after 2 years. None of the patients treated by radiotherapy were alive after 2 years. 29% of the patients treated by surgery survived for 2 years, but none of them were alive after 5 years, essentially as a result of local recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)