Clinical observations indicate that persons with eating disorders exhibit many psychopathologic symptoms such as difficulty with impulse control and depressed mood associated with impaired regulation of serotonin (5-HT) synaptic function in the central nervous system. In this study, we focused on the relationship between the 5-HT-induced calcium response in platelets and the clinical symptoms. While age, body weight, and severity of depressive symptoms were not correlated with 5-HT-induced response, there was an enhanced response in patients with bulimic symptoms or other impulsive behaviors. Moreover, patients with multi-impulsive behaviors had a significantly higher maximal increase than patients with uni-impulsive behavior, i.e., those who had only bulimic symptoms, as well as non-impulsive patients, and controls. Considering these results, the 5-HT-induced response may be related to difficulty with impulse control in general rather than bulimic eating attitudes specifically.