Histopathological criteria are usually sufficient for the accurate distinction of benign form malignant renal tumors. A minority of cases however, poses a vexing diagnostic dilemma. Recent studies suggest that caveolin, a scaffolding cell membrane protein may prove helpful in predicting the behavior of these neoplasms. We analyzed a series of 40 renal tumors of which 7 were clear cell and 6 granular Renal Cell Carcinomas (RCC), 10 cases of Papillary Carcinoma (PCC), 4 cases of Chromophobe Renal cell carcinomas (CRCR), 11 cases of Oncocytomas (OC) and 2 cases of Collecting Duct Carcinomas (CDC). The distribution of immunoreactivity was analyzed by quantifying caveolin cell membrane staining in each case. There was a statistically significant difference in the expression of caveolin-1 between oncocytoma with a mean labeling index of 91.7 and the cases of malignant renal tumors with a mean labeling index of 26.9 for RCC, 24 for CDC, 21 for CRCR, and 19.2 for PCC. The results suggest an association between loss of caveolin expression among malignant renal tumors that might be useful in distinguishing oncocytoma from malignant renal tumors and possibly implicates this peptide in their pathogenesis.