Extravasation of glycine irrigant during percutaneous ultrasonic lithotripsy has caused a transurethral resection syndrome consisting of hypertension, confusion and hyponatremia. With a rabbit model this complication is recreated with the intraperitoneal instillation of 1.5 per cent glycine solution tagged with 14carbon-glycine. Significant quantitative absorption of glycine into blood and other organs is demonstrated. A review of the literature reveals few guidelines as to the choice of irrigant for intrarenal endoscopy. Since this procedure involves no electric current it is suggested that physiological saline rather than glycine be used for ultrasonic stone disintegration.