We used single photon emission computed tomography (SPECT) with Tc-99m-HMPAO to examine the characteristics of regional cerebral blood flow (rCBF) in five patients with bulimia nervosa (BN), eight patients with anorexia nervosa (AN), and in nine healthy controls. The SPECT examinations were performed before and after food intake stimulus, and the values of the corrected ratio (R) for rCBF in 10 cerebral cortical regions before (Rbefore) and after eating (Rafter) were calculated. The asymmetry indices (AI) of the R values for the left and right side of each cortical region and the percent change from Rbefore to Rafter (%change) were computed. In comparison with the other two groups, BN patients showed significantly higher Rbefore values in the bilateral inferior frontal and left temporal regions. The AN patients showed significantly lower Rbefore values in the left parietal region than the control group. There were no significant differences in Rafter values among the three groups. The %change values in the AN group showed the greatest increase in 9 out of the 10 regions. In contrast to the positive values obtained from the 10 regions observed in the AN group, 5 out of the 10 regions in the BN group showed negative values. Among the three groups, significant differences in %change were observed on both sides of the inferior frontal, temporal, parietal, and occipital regions. These findings indicate that differences in cerebral function of BN and AN patients can be characterized through SPECT imaging.