In addition to pre- and postcontrast renal CT scans, early bolus-enhanced spiral scans during demarcation of the corticomedullary junction were acquired in 85 patients. The diagnostic value and drawbacks of the three imaging series in the evaluation of renal disease were assessed. Renal calcifications and calculus disease detected at precontrast scans (18%) were obscured after contrast administration and excretion in most cases. In the detection of renal lesions bolus-enhanced spiral CT and delayed postcontrast scans had an identical diagnostic yield (94%). Bolus-enhanced spiral CT was superior in the assessment of lesion vascularity and vascular anatomy as well as opacification of renal arteries (95%) and veins (85%). Delayed postcontrast scans were indispensable to delineate medullary or parapelvic cysts as well as anatomic abnormalities or tumors of the renal pelvis (17% of all lesions). Routine renal CT of the kidneys should consist of precontrast images and delayed postcontrast spiral scans. Bolus-enhanced spiral scans are advised to assess lesion vascularity of renal veins.