Nephroblastoma is one of the most frequent tumours of child age. In its diagnosis and assessment of the stage of the disease participate in a significant way imaging methods, in particular ultraso- nography and CT. Nephroblastomas are as a rule at the time of assessment of the diagnosis very extensive. They develop from the renal parenchyma, are usually well defined with a pseudocapsule, frequently they contain necroses and haemorrhages. They dislocate, rotate and disfigure the calycino-pelvical system of the affected kidney, they compress and dislocate the preserved part of the renal parenchyma. They may penetrate into the renal vein and the vena cava inferior and form a so-called tumourous thrombus. Dextrolateral tumours dislocate as a rule the vena cava inferior and usually compress its lumen. Only extensive nephroblastomas extend beyond the median line. From the differential diagnostic aspect it is important to differentiate in particular retroperitoneal neuroblastomas. Preoperative assessment of the contralateral kidney focused in particular on its function and possible tumourous affection is important. An integral part of the imaging diagnosis of nephroblastoma is also the baseline examination of the lungs by a native X-ray picture and subsequently by CT.

        Key words: nephroblastoma - Wilm´s tumour - imaging methods