Sixteen healthy men received iohexol intravenously at a concentration of 346 mg of iodine/mL. Doses of 500, 750, 1000, and 1500 mg of iodine/kg of body weight were administered to four volunteers each. Neither clearance nor percent of dose excreted in the urine showed any significant correlation with size of the dose. The overall mean (+/- SD) renal and total body clearances were 120 +/- 18.6 and 131 +/- 18.6 mL/min, respectively. The overall mean apparent volume of distribution was 165 (+/- 30.7) mL/kg. Urine contained 92.3 +/- 4.4% of the dose. Most of the drug (89.9%) was excreted within the first 12 h. An open three-compartment body model gave the best fit to the experimental data. The mean apparent first-order terminal elimination (gamma-phase) half-life was 12.6 h.