Right ventricular hypertrophy is a rare pathology in newborns. Known aetiological factors of cardiac hypertrophy in neonates include hypertrophic cardiomyopathy, congenital heart disease, gestational diabetes, and premature closure of the ductus arteriosus. We present a clinical case of a term neonate diagnosed with a severe hypertrophy of the right ventricles with an undetermined cause, which disappeared within a five-week period.