A solitary native kidney is generally considered to be an absolute contraindication to percutaneous biopsy. However, technical advances, such as real-time ultrasound guidance and automated core biopsy systems, provide an excellent safety profile with an extremely low risk of catastrophic complications and have caused some investigators to call for a reassessment of this contraindication. The overall results at our institution are reported. Of 544 consecutive native and allograft kidney biopsies conducted over 2.5 years, 482 were performed with an automated core biopsy system and 281 also used real-time ultrasound guidance. The overall complication rate was 5.3%. Transient gross hematuria was seen in 4.4% and hematoma was seen in 1.5%; no patient experienced loss of kidney function and there were no deaths. We recently have begun to perform percutaneous biopsy of solitary native kidneys in carefully selected patients. To date, nine such procedures have been attempted, with success in eight cases. One patient had transient gross hematuria; no other complications were noted. This encouraging preliminary experience suggests that otherwise uncomplicated adult patients with a solitary kidney might be considered for percutaneous biopsy. It now seems appropriate to prospectively evaluate percutaneous biopsy of solitary kidneys in a larger cohort of unselected patients.