Gastroparesis is a kind of stomach disease that is identified with delay of gastric emptying of solid food without mechanical obstruction. The disease is diagnosed by invasive techniques. Scintigraphy imaging technique is accepted as the gold standard in diagnosis although having many disadvantages. In this study. non invasive EGG signals were obtained from gastroparesis patients and healthy volunteers. Power Spectral Density (PSD) graphs were obtained for purpose of determining feature in frequency axis for diagnosis. PSD method for which parametric method that is used to the signals, was determined using Cramer-Rao Lower Bound (CRLB) method.