The simultaneous discovery of two corpses at the same scene obliges the forensic pathologist to consider many circumstances. First, the hypothesis of homicide/crime has to be investigated. However, when the circumstances, autopsy, histological data and toxicological and biochemical analyses suggest a natural cause of death, Philemon and Baucis syndrome should be considered. While a few cases of Philemon and Baucis deaths involving couples of spouses have been reported in the literature, only one paper describes the simultaneous deaths of two siblings. The case presented here concerns the death of two siblings who were found in an advanced stage of decomposition in their apartment, which had been allocated to them by social services. The victims were known to be living in conditions of social and economic deprivation and to be suffering from psychiatric disorders. The first suspected cause of death was malnutrition. However, this was excluded by complete autopsy, histological studies and, especially, biochemical investigations, which excluded starvation ketoacidosis. Moreover, no evidence of trauma or poisoning was found in either of the bodies. Despite the advanced stage of decomposition, one of the bodies presented with histological signs of myocardial sclerosis, left ventricular hypertrophy and contraction band necrosis, suggesting that the mechanism of death involved a fatal arrhythmia. The circumstances and the post-mortem findings were highly suggestive of Philemon and Baucis syndrome.