The case presented here is a three-month-old male infant with the Beckwith-Wiedemann's syndrome. Clinically, the patient was characterized by macroglossia, visceromegaly, umbilical hernia, microcephalus and other multiple malformations such as facial flame nevus or ear lobe grooves. The patient died of bronchopneumonia at the age of three months, and an autopsy was performed. Morphological examination revealed adrenal cytomegaly, hyperplasia and hypertrophy of the pancreatic islets, adrenal rest tissue in the right testis or hypertrophy of muscle fibers of the tongue associated with fibrous degenerative change, in addition to bronchopneumonia of the lung, causing his death. On electron microscopical examination, the cytomegalic cell of the adrenal was characteristic of large pleomorphic nucleus and granular substances with high density in the cytoplasm. In this case, thorough histologic search revealed no evidence of tumorous growth in the organs, though the exomphalos-macroglossia-gigantism syndrome has been of interest in its relationship to the occasional occurrence of Wilms tumor, adrenal carcinoma or other tumors.