Based on a retrospective series of 7 patients (6 men and 1 woman) with a mean age of 56.5 years, the authors describe the clinical, radiological and pathological features and the clinical course of sarcomatoid renal cancers in adults. They stress the severity of this type of tumour, due to the fact that the lesion is usually very advanced at the time of diagnosis (3 cases of Robson's stage III tumours and 4 stage IV tumours). Radiological assessment frequently reveals calcifications within the mass (4 out of 7 patients). Surgical excision is sometimes impossible and, when it can be performed, it has little influence on the prognosis or the survival.