Percutaneous image-guided parenchymal renal biopsy has been used to detect the different pathologies of renal parenchyma, to define the degree of reversible changes, and to define when the medical treatment fails. Percutaneous core needle renal biopsy has been reported to have a higher diagnostic yield compared to fine needle aspiration. Percutaneous core needle renal biopsy is usually based on tissue sampling under guidance of either sonography or computed tomography. Renal parenchymal biopsy can be done either with a coaxial or noncoaxial technique. In coaxial technique, the introducing needle is placed in the renal parenchyma; then, multiple tissue sampling can be performed throughout the same tract. Alternatively, in noncoaxial technique, biopsy needle is inserted repeatedly for each tissue sampling. Although there are some reports regarding the comparison of coaxial and noncoaxial methods of renal mass biopsy, comparison of the two methods in renal parenchymal biopsy has not yet been described in the literature. In this prospective study, the investigators sought to compare the procedural time and the complication rate of coaxial technique with those of noncoaxial technique in percutaneous renal parenchymal biopsy.