In Switzerland the cases of sudden unexpected death and especially of relatively young people are reported to the judge who orders a forensic autopsy. In some cases, the cause of death remains however unexplained after a classical autopsy and toxicological analyses. In these cases, the cause of death may be related to potentially inherited arrhythmias. According to the literature, the cases of unexpected arrhythmogenic death are estimated to represent 5-10 % of all sudden deaths. The advances in molecular biology have opened new diagnostic perspectives in forensic pathology. In fact, with the appearance of molecular autopsy, it becomes possible to detect the cause of death related to genetic origin and without morphological substrate diagnosed at autopsy as for example cardiac channelopathies. To illustrate this concept, two cases with no evident cause of death found at classical autopsy are presented, one of a 6-month-baby and a second one of a 24-year-old woman. For both victims SCN5A mutations have been detected. One of these mutations has been already described in the literature, whereas the pathogenicity of the second one was determined by analysis of the mutationinduced alteration in cardiac sodium current. However, the molecular diagnosis concerns not only cardiac diseases. Indeed, since the apparition of pharmacogenetics it is considered that both drug disposition and response are individually variable and some genetically vulnerable victims may die with extremely low drug levels found at toxicological analyses. It is also evident that chronic drug abusers may have increased tolerance for high levels of substances detected in their body. Thus, the autopsy findings as well as the results of toxicological and genetic analyses need to be interpreted together in order to decide which case could be really considered as a sudden cardiac death. The molecular diagnosis is important to clarify a case, especially in cases without morphological substrate and makes also possible the detection of the genetic predisposition to sudden deaths of relatives. In this respect, the information provided by genetic analysis places the forensic pathologist in an interdisciplinary collaboration. At the University of Lausanne a multicenter team has been created between departments of forensic pathology, cardiology, and genetics in order to diagnose and prevent the cardiovascular diseases in relatives. The role of the forensic pathologist in this team as well as the legal aspects of postmortem genetic analyses will be discussed.