A frequently fatal, although rare, side effect of cephalosporin antibiotics is noninfectious myocarditis. We report two cases of hypersensitivity myocarditis secondary to administration of cephalosporin antibiotics. In both cases, acute hypersensitivity myocarditis was not suspected clinically, and the diagnosis was made postmortem. Histology revealed intense eosinophilic infiltration of the endomyocardium with eosinophil degranulation and myocyte damage, Clinically, death in both cases was due to cardiac failure. When suspected early, appropriate management may be lifesaving.