Fundoplication of the stomach is an established surgical treatment of gastroesophageal reflux. Its mechanism of action remains unclear. To assess its effect on gastric emptying, 21 patients (11 men, 10 women), median age 47 years (range 19-72), underwent a gastric emptying study before and 6 months after fundoplication. Gastric emptying studies were performed after an overnight fast using a dual isotope technic. Solid and liquid emptying rates were assessed over 120 minutes. The time taken for 50% of the liquid marker to leave the gastric region was a median of 22 minutes before surgery (range 9-35) and 13 minutes after surgery (range 9-27) (p less than 0.01). The percentage of solid remaining in the stomach 100 minutes after ingestion was 50% before surgery (range 19-90) and 44% after surgery (range 5-89) (p less than 0.01). We conclude that gastric emptying of both solids and liquids tends to be increased following fundoplication. This observation suggests a further mechanism for the efficacy of this operation in the treatment of gastroesophageal reflux.