The utility of scintigraphic views obtained after administration of sodium bicarbonate-citric acid-simethicone crystals (E-Z-GAS) for the determination of gastric extra-hepatic perfusion was evaluated in 20 technetium-99m macroaggregated albumin hepatic arterial perfusion studies performed in 19 patients. These crystals produce carbon dioxide gas, distend the stomach, and allow better delineation of gastric activity (extrahepatic perfusion to the stomach). Conversely, a lack of change in activity in the left upper quadrant after the effervescent crystals have been ingested suggests no gastric activity (and no extrahepatic perfusion to the stomach). These 'air-contrast' views added useful information in 16 of 20 studies. In three cases prior hepatic arterial perfusion studies without air contrast were misinterpreted as lacking extrahepatic perfusion, which was only recognized on subsequent studies through the use of the air-contrast views. In another case extrahepatic perfusion was erroneously diagnosed on a hepatic arterial perfusion study without air contrast, with a follow-up air-contrast hepatic arterial perfusion study showing this to have been a false-positive diagnosis. Air-contrast views of the stomach can be extremely helpful in verifying or excluding the diagnosis of gastric extrahepatic perfusion on technetium-99m macroaggregated albumin hepatic arterial perfusion studies.