In the past 4 years we have carried out 650 percutaneous renal biopsies (PRB), 54 on transplanted and 596 on native kidneys. PRB was performed with a 14-gauge one-piece disposable needle that was introduced free-handedly into the lumbar wall without any form of fixed guidance or support. Ultrasound was used to locate the kidney pole and to follow the progression of the needle tip in the renal parenchyma. The time needed for the whole procedure was about 5 min. The tissue specimen was adequate for histological evaluation in 98.8% of the cases. The prevalence of post-biospy complications (haematuria, pain, anaemia) was 2.5%. Haematuria was not a common complication (1.6%) in our series, whereas clinically silent perirenal haematoma was common. Mild perirenal bleeding (volume