Endomyocardial fibrosis is characterized by the formation of fibrous tissue in the endocardium. Although the disease may affect both ventricles, isolated or not, the right ventricle is more frequently involved. Endocardial fibrosis may be present in the entire ventricular cavity, being usually more marked in the apical region and right ventricular inflow tract. Its etiology, however, still remains unknown. Background-Reports on endomyocardial fibrosis in pediatric patients are not common. It is more frequent from the fourth year of age on, with few reports in the first 2 years of life. This case aimed at reporting right ventricular endomyocardial fibrosis in 7 days old male neonate, in addition to discussing the etiopathogenesis and future perspective of the disease.