The gastric emptying times associated with three whey-based formulas were significantly shorter than that associated with a casein-based formula in nine gastrostomy-fed patients with spastic quadriplegia (p less than 0.001). Patients fed whey-based formulas had significantly fewer episodes of emesis than when they were fed casein-based formula (p less than 0.001). We conclude that whey-based formulas reduce the frequency of emesis by improving the rate of gastric emptying.