Death due to gas inhalation is accidental or suicidal. Natural gas can be a cause of death as a result of oxygen replacement in the atmosphere. Three male victims who were killed from gas inhalation are described in this study. One 19-year-old man attempted suicide using a combination of plastic bag suffocation and natural gas tube in his mouth. The other victim (24 years old man) attempted suicide by natural gas inhalation, and the cause of death of the third victim was inhalation of the vapor from a furnace that contained crude oil or gasoline. Methanol was detected in blood and liver samples by headspace gas chromatography (HSGC) and headspace gas chromatography-mass spectrometry (HSGCMS). Carboxyhemoglobin (CO-Hb) and other drugs and poisons were not detected in blood and liver samples.