Objectives: To determine conventional computed tomography (CT) signs in the diagnosis and staging of upper urinary tract tumors (UUTTs). Methods: Retrospective study was made of the CTs of 82 patients diagnosed with UUTTs. Nine CT signs were defined and compared with the pathology of the surgical specimen. A χ2 test was used for statistical analyses. Results: We reviewed the CTs of 93 UUTTs in 82 patients, of which 36% were invasive and 12% had positive lymph nodes. Renal parenchymal invasion was found in 82% of high-grade and in 18% of low-grade tumors (p = 0.001). 94% of the tumors with signs of renal parenchymal invasion were invasive (p Conclusions: CT offers good sensitivity (87.5%) and specificity (98%) in the detection of lymph node involvement, and 64% sensitivity and 97% specificity for the detection of renal tumor invasion.