The purposes of this study were to use a noninvasive scintigraphic technique to measure gastric emptying of liquids and solids simultaneously, to study the interactions between emptying of the liquid and solid components of meals in normal subjects, and to employ dual isotope gastric scintigraphy to evaluate gastric emptying of liquids and solids in patients with clinical evidence of gastric outlet obstruction. The solid component of the test meal consisted of chicken liver, labeled in vivo with Tc-99m sulfur colloid, and the liquid component was water mixed with In-111 DTPA. The rates of emptying were quantitated using a gamma camera on line to a digital computer. Twenty normal subjects were studied using this combined solid-liquid meal. Ten of them also ingested a liquid meal alone and ten a solid meal alone. Liquid emptied from the stomach significantly more rapidly than did solids. The emptying curve for liquids was exponential compared to a linear emptying curve for solids. The gastric emptying rate of the liquid component was slowed significantly by simultaneous ingestion of solids, but the emptying rate of solids was not affected by liquids. Several patients with clinical gastric outlet obstruction were evaluated. Both combined and selective abnormalities for gastric emptying of liquids and solids were demonstrated.