South Egypt Cancer Institute, Assuit University, Egypt\r\n\r\n\r\nBiopsy plays an important role in the care of patients with a renal mass. As the biopsy results are used to confirm the diagnosis of renal cancers, metastases, and infections, and the biopsy can help subtype and grade many primary renal cancers. Use of percutaneous biopsy to identify which masses are benign, and in some patients which masses are more or less aggressive. It is essential to identify tumor histology in the setting of metastatic disease. Before image-guided biopsy, a cross-sectional imaging studies is needed to determine the safest approach to the targeted lesion, the shortest distance to the lesion without crossing additional organs, large vessels, or vital structures is optimal. CT guided biopsy has the advantage of better resolution and tissue contrast, Is better able to localize the lesion and the needle tip and identify the surrounding critical structures (pleural space and bowel). In the last 10 years there were little number of published articles about role of percutaneous biopsy in renal masses, Aim of our study: to evaluate the role of CT-guided percutaneous biopsy in diagnoses of different renal tumors either benign or malignant ( primary or secondary) masses. Twenty patients were included in this study, These patients were presented with renal tumor of indeterminate diagnoses according to the imaging modalities (US, CT or MRI), CT-guided percutaneous biopsy was performed to evaluate the nature of this renal tumor after pre and post contrast CT examination. Biopsy yield, complications and impact of patient`s management were analyzed. The diagnostic capability of CT-guided percutaneous biopsy was (90%), non representative biopsy was demonstrated in 2 patients (10%) who underwent 2nd trial of biopsy with incidence of minor complications (5%). Finally, The CT guided percutaneous biopsy can help in accurate and specific diagnosis of renal tumors with subsequent impact on their clinical management.\r\n