Gallium nitrate, administered intravenously to patients with advanced cancer, produced renal functional abnormalities consistently at a dose of 750 mg/m2. The toxicity at that dose could be modified by fluid loading and osmotic diuresis. Pharmacokinetic studies revealed a biphasic half-life, (T 1/2 alpha = 87 minutes and T 1/2 beta = 24.5 hours). Osmotic diuresis reduced the urinary concentration of gallium but did not affect serum levels or clearance.