Hypersensitivity myocarditis may result from an allergic reaction to a variety of agents such as antibiotics, anticonvulsants and diuretics. A diagnosis of hypersensitivity myocarditis should be considered in any patient with an ongoing allergic reaction to a drug, evidence of peripheral eosinophilia, an appearance of new electrocardiographic changes, mildly elevated cardiac enzyme, mild cardiomegaly on chest X-ray or unexplained tachycardia. This condition is rarely recognized clinically although it is occasionally diagnosed on endomyocardial biopsy. We report a 25 year-old woman with hypersensitivity myocarditis, which was diagnosed by endomyo-cardial biopsy and successfully treated by immunosuppression therapy with corticosteroids.