Patients receiving total intravenous nutrition have inert gallbladders; gallbladder sludge and gallstones often develop, but are preventable if gallbladder emptying can be improved. We measured the effect of giving rapid intravenous infusions of aminoacid solutions in eight normal subjects. Four regimens were tested (250 mL over 30 min, 250 mL over 10 min, 125 mL over 5 min, and 50 mL over 5 min). Gallbladder emptying, as measured by ultrasound and cholecystokinin release, depended on both the amount and the rate of aminoacid infusion. Rapid infusion of 125 mL of an aminoacid mixture (Synthamin 14 without electrolytes) over 5 min (2.1 g per min) produced a 64% reduction in gallbladder volume within 30 min, whereas a 50 mL infusion over 5 min produced only a 22% reduction. Intermittent rapid infusion of small amounts of aminoacids may prevent gallstones in patients receiving intravenous nutrition.