The active ingredient in Pepto-Bismol (PB) (Norwich-Eaton), a common antidiarrheal, is bismuth subsalicylate. The absorption of salicylate after oral PB was studied in six fasted men. Plasma concentrations of total salicylate and the urinary excretion profile of salicylate were determined as a function of time and dose. After 60 ml PB, 500.1 +/- 33.6 mg (mean +/- SD) salicylate were recovered in urine, representing 95.0 +/- 6.4% of salicylic acid equivalents in 60 ml of the formulation. Peak plasma salicylate levels were reached 0.5 to 3 hr after ingestion and averaged 40.1 +/- 17.3 micrograms/ml. Absorption of salicylate was also essentially complete after 15- and 30-ml doses of the antidiarrheal preparation, and a linear relationship between dose and recovery of salicylate in the urine was found. Salicylate kinetics was nonlinear after a multiple-dose regimen of 60 ml every 6 hr for five doses.