The authors prospectively and retrospectively mutually compared the diagnostic value of urography, ultrasonography (USG), and computer tomography (CT) in four patients, with the diagnosis misstated prior to operation. The most valuable findings were provided by CT. Mere utilization of these methods does not exclude the possibility of diagnostic misstatements. In three patients the ultimate diagnosis was assessed on the basis of operative revision and in one patient, by means of cytologic examination of the renal punctate. Owing to retrospective evaluation of examinations, diagnostically valuable symptoms which could have lead to the correct diagnosis, were distinguished. Hence, examinations must necessarily be evaluated in complex with the general clinical state. (Fig. 6, Ref. 14.).