The use of real-time ultrasound-guided renal biopsy is believed to be superior to blind biopsy, but there are few reports comparing the two techniques. The goal of the present study was to compare the outcomes of ultrasound-guided and blind renal biopsies at a single teaching institution, in terms of adequacy of tissue yield and frequency of hemorrhagic complications. We reviewed retrospectively the outcomes of all patients undergoing a percutaneous native kidney biopsy during a 2-year period (January 1, 2004 to December 31, 2005). Of 129 renal biopsies, 65 were ultrasound-guided and 64 were performed by the blind technique. All biopsies were performed by nephrology fellows under direct faculty supervision. The two patient groups were comparable in terms of age, sex, race, diabetes, hypertension, serum creatinine, and hematocrit. The mean number of glomeruli per biopsy was higher in the ultrasound-guided group than in the patients with a blind biopsy (18 +/- 9 versus 11 +/- 9, p = 0.0001). An inadequate tissue sample requiring repeat biopsy occurred in 0% of the ultrasound-guided biopsies and 16% of the blind biopsies (p = 0.0006). Large hematomas requiring vascular intervention or transfusion were less frequent in the ultrasound-guided biopsies (0% versus 11%, p = 0.006). The hematocrit 24 hours postbiopsy was higher in the ultrasound-guided biopsies when compared with the blind biopsies (32 +/- 5% versus 30 +/- 4%, p = 0.04). When compared with blind renal biopsy, real-time ultrasound-guided percutaneous renal biopsy provides a superior yield of kidney tissue and results in fewer hemorrhagic complications. Real-time ultrasound-guided renal biopsy is the preferred technique.