Magnetic resonance (MR) imaging has been proposed as a noninvasive alternative to vena cavography and computed tomography for the detection of venous extension of renal adenocarcinoma. However, spin-echo MR images may be compromised by the presence of flow-related artifacts, extrinsic compression, and respiratory or cardiac motion artifacts. Use of gradient-recalled echo (GRE) sequences is advantageous for imaging of vascular structures. To investigate the detection of vascular extension of tumor with the GRE technique, findings in the preoperative GRE MR images of 26 patients with renal adenocarcinoma were compared with findings at surgery and pathologic examination. Vena cava thrombus was correctly identified in 13 of 13 patients (100%). Renal vein thrombus was correctly identified in 23 of 26 patients (88%), and right atrial thrombus was correctly identified in four of five patients (80%). Use of GRE sequences allows accurate assessment of vascular structures that is sufficient for surgical planning.