During a cardiac blood pool study (Tc-99m erythrocytes), there was an apparent "cold" area in the left lobe of the liver. At one hour, the prior void appeared to have filled in, suggesting an intrahepatic hemangioma. However, the changing pattern of radioactivity, and its shape, indicated that this actually represented Tc-99m pertechnetate in the gastric wall and stomach cavity. In a second case, the interval between intravenous injection of stannous pyrophosphate and Tc-99m pertechnetate was prolonged. Changing activity, again in the gastric wall and cavity, obscured part of the liver. This cleared with time, allowing hepatic evaluation. Thus, gastric pertechnetate can contribute to blood pool images of the heart or liver and multiple images may be needed to separate this component from nearby tissues.