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. 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 showed 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 here a rare case of simultaneous onset of an acute cholecystitis and pericarditis associated with a marked eosinophilia caused by parasitic infection.