Paired studies of gastric emptying were performed in 10 healthy volunteers using a scintiscanning technique which provides information about the rate of emptying of both the liquid and solid components of a standard meal. Emptying rates of both components were not significantly different after oral administration of 400 mg cimetidine than after placebo. The increase in serum gastrin concentration produced by the meal was significantly greater after cimetidine than after placebo but there was no relationship between individual cimetidine-placebo differences in gastrin response and the corresponding cimetidine-placebo differences in rates of emptying. A positive correlation was demonstrated between the gastric emptying rate of the liquid component and the 1 h cimetidine absorption, indicating that normal individual variation in gastric emptying is probably responsible for much of the normal individual variation in the rate of cimetidine absorption.