Eosinophilic cholecystitis (EC) is a rare entity that presents in a manner comparable to acute cholecystitis. The diagnosis is based on classical symptoms of cholecystitis with the presence of >90% eosinophilic infiltration within the gallbladder. We report the case of a 29-yr-old man who presented with unremitting right upper quadrant pain, chills, and loss of appetite. After confirmation of the diagnosis with ultrasound and hepatobiliary scan (HIDA), a cholecystectomy was performed. Pathologic examination of the excised gallbladder demonstrated submucosal infiltration with eosinophils, consistent with EC. Peripheral eosinophilia was not observed; the subject's blood eosinophil count did not exceed 3% during the period of observation. The patient was discharged with no further symptoms. Cases of EC have been infrequently reported since its original description in 1949. EC has been reported alone or in combination with manifestations such as eosinophilic cholangitis, hypereosinophilic syndromes (HES), and parasitic infestations. The patient described herein gave no indications of such previously suggested causes of EC. This report illustrates an authentic case of idiopathic EC.