Authors analyse the value of intravenous pyelography, ultrasonography, computed tomography, angiography and fine needle aspiration biopsy in the detection, differentiation and staging of renal space-occupying lesions, on the basis of examinations performed in 158 patients, in comparison with results of surgery and/or clinical follow up. Their conclusion is that ultrasonography plays a major role in the detection and differentiation of these lesions, intravenous pyelography is only a complementary method, while computed tomography can provide diagnosis in cases with uncertain ultrasonographic findings. Staging has to be based on computed tomography. The role of angiography and fine needle aspiration biopsy is limited they need to be performed in a few selected cases only.