Percutaneous renal biopsy may be complicated by hemorrhage. Patients are frequently hospitalized for overnight observation. We evaluated prospectively the feasibility and safety of an outpatient renal biopsy protocol. During a 20-month period, 100 consecutive patients underwent outpatient renal biopsy using a standardized protocol. The biopsy was performed by Nephrology Fellows, under direct faculty supervision. All biopsies were carried out under real-time ultrasound guidance with a 16-gauge spring-loaded biopsy gun, and followed immediately by color Doppler ultrasound to exclude active bleeding. Blood pressure, heart rate, hemoglobin, and hematocrit were monitored for 8 hours postbiopsy. If there were no complications, the patients were discharged home after the observation period. A total of 91 patients required one or two needle passes, and nine needed three or four passes. A mean of 12.7 +/- 9.7 glomeruli were obtained per patient. No major complications were encountered. A small (<2 x 2 cm) perinephric hematoma was observed postbiopsy in 13 patients. Four patients were hospitalized for overnight observation due to a >4% decrease in their hematocrit, but none required a transfusion or intervention. No patient experienced a delayed biopsy-related complication. Outpatient, real-time, ultrasound-guided percutaneous renal biopsy is safe and effective, and minimizes the need for postbiopsy hospitalization. It can result in significant cost savings without exposing the patients to an increased risk of complications.