Although the etiology of eosinophilic cholecystitis is still obscure, the postulated causes include allergies,parasites, hypereosinophilic syndrome, and eosinophilic gastroenteritis. It is sometimes accompanied by several complications, but a simultaneous onset with pericarditis is very rares. A 28-year-old woman complained of acute right hypocondrial pain and dyspnea associated with systemic eruption. Several imaging modalities revealed acute cholecystitis and pericarditis with massive pericardial effusion. A marked peripheral blood eosinophilia was observed, and the eruption was diagnosed as urticaria. Her serum had a high titer of antibody against Ascaris lumbricoides. Treatment with albendazole drastically improved all clinical manifestations along with normalization of the imaging features and eosinophilia. We report herein a rare case of simultaneous onset of acute cholecystitis and pericarditis associated with a marked eosinophilia caused by parasitic infection.