We describe our experience with real-time ultrasound as a localization and guidance tool for percutaneous renal biopsy. Two hundred biopsies performed between June 1983 and January 1990 were reviewed retrospectively. Nephrology fellows performed 83.5% of the biopsies. The average age of the patients was 43 +/- 17 years (range 6-80) and renal insufficiency (serum creatinine greater than or equal to 1.3 mg, %) was present in approximately 60% of patients biopsied. Primary indications for biopsy were to evaluate proteinuria (46.5%) and renal manifestation of systemic lupus erythematosus (24%). Material for light microscopy, immunofluorescence, and electron microscopy was obtained in 99.5, 95.0 and 98.0% of cases, respectively. Adequate tissue for histologic diagnosis was obtained in 97.5% of patients. Primary diagnosis was glomerulonephritis in 77.9% of cases. Complications were assessed and separated by severity. Total complications were observed in 13.7% of patients with 8.1% of these being minor complications (not requiring blood transfusion) and 5.6% being major complications which required blood transfusions. Bleeding complications requiring massive blood transfusion and/or therapeutic radiologic intervention were seen in 1.5% of patients. We could find no significant difference with respect to age, serum creatinine, or coagulation parameters between patients with or without complications due to percutaneous renal biopsy. We conclude that real-time ultrasound is a safe, accurate method in localizing the kidney for percutaneous renal biopsy. However, patients must still be observed carefully post biopsy for potential complications.