Asphyxia by suffocating gases, that is, methane or carbon dioxide, is characterized by the displacement of oxygen from inspired air. Thus, the cells are unable to receive oxygen and, as a consequence, are affected by acute hypoxemic hypoxia. The brain suffers because of the hypoxemic state, the subject become unconscious, and then, respiration arrest occurs, followed by cardiac arrest. This is the physiopathologic mechanism leading to death.We report a case of a 35-year-old man found dead at home with his mouth containing a tube linked to the domestic methane gas system originating from the wall, sealed with packing tape.