An autopsy case of sudden death in a 33-year-old man with neurofibromatosis type 1 (von Recklinghausen disease), pheochromocytoma, and myocarditis is reported. The decedent was found in his bedroom in cardiopulmonary arrest. Polypoid, elastic dermal papules on the neck, chest, abdomen, and back, and flat dark-brown macules on the chest and abdomen were observed. Flat, ovoid, dark-brown freckles were present in both axillae. Examination of the right adrenal gland revealed a tumor measuring 5 cm × 5 cm × 3 cm. Microscopic examination of the myocardium revealed moderate neutrophilic and lymphocytic infiltrates. In the right adrenal gland, tumor cells contained abundant granular eosinophilic cytoplasm and exhibited cell-nesting with an alveolar pattern (Zellballen). Polygonal cells were seen together with rich vascular networks. Immunohistochemical analyses showed cells diffusely positive for chromogranin A and dopamine β-hydroxylase. Furthermore, blood from the right heart and the right common iliac vein contained high concentrations of serum epinephrine, norepinephrine, and dopamine. Death was attributed to adrenal crisis: circulatory failure caused by excessive catecholamines produced by the pheochromocytoma. In addition, myocarditis, which had been induced chronically by catecholamines, would have also contributed adversely to the clinical course. Pheochromocytoma and myocarditis should be considered when sudden death occurs in the setting of neurofibromatosis type 1.