The goal of this presentation is to underline the difficulty of diagnosis of SIDS. According to San Diego SIDS diagnostic criteria, a clinical, anamnestic, circumstantial, and autoptic investigation must be performed. In most of cases death remains unjustified after the diagnostic procedures and SIDS is unresolved. This presentation concerns a case of resolved SIDS, in which the postmortem investigation led to diagnosis of dilated cardiomyopathy (DCM) with endocardial fibroelastosis, associated to tubular hypoplasia of the aorta and inborn errors of metabolism. This presentation will impact the forensic science community by showing the difficulty to diagnose clinical silent cardiomyopathy in children younger than one year old, and so an accurate clinical, anamnestic, circumstantial and instrumental investigation can lead to a timely diagnosis of DCM in life.