A case of tranilast (Rizaben)-induced cystitis accompanied with possibly hypereosinophilic heart syndrome was described. A 75-year-old male, who had been taking tranilast for allergic dermatitis for two months, was admitted for severe bladder stimulating symptoms which was unresponsive to antibiotic therapies. Clinical examination revealed tenderness of the prostate, aseptic pyuria, eosinophilia, liver dysfunction and electrocardiographic disorders including atrial fibrillation, T-wave inversions and lowered ST segment without any cardiac symptoms. Cystitis symptoms, pyuria, eosinophilia and liver dysfunction improved within several days after discontinuance of tranilast, and ST-T changes on ECG gradually normalized within a few months. Tranilast-induced cystitis has been demonstrated as a type of eosinophilic cystitis. Since pathologic findings of eosinophilic cystitis and hypereosinophilic heart syndrome are markedly similar and all symptoms and signs disappeared after deprivation of tranilast, it appears likely that eosinophilic inflammation was induced to the heart, liver, bladder and prostate of the current patient by tranilast.