Impedance electrogastrography (IE) is a noninvasive method to assess gastric contractile activity. This indirect method uses a four-terminal impedance measuring method to determine impedance variations of the gastric region of the torso. These variations can be related to changes in the stomach shape and, therefore, to gastric contractions. Because the impedance variations are very small, the placement of the measuring electrodes on the skin is critical. In this study, a three-dimensional resistor model consisting of 4,466 resistors was used to simulate the human torso. The model was implemented on a personal computer, and the experimentally obtained optimal electrode locations were found to be superior to the commonly used ones. Measurements of volunteers confirmed these findings.