Suicidal suffocation by forced oxygen depletion (environmental hypoxia) with carbon dioxide (CO2) and with propane is discussed in two cases. No toxicologic proof was available with the former and circumstantial evidence weighed heavily. The latter case demonstrated inhaled propane by an on-scene transthoracic aspirate; all other toxicology specimens, including brain, liver, blood, kidney, fat, and vitreous, did not contain hydrocarbons. This second fatality was complicated by multi-agent overdose, including diphenhydramine, fluoxetine (Prozac), and nordiazepam. The designation of these deaths as due to oxygen depletion involved careful scrutiny of the autopsy, toxicologic, and scene findings. Complete analysis of all factors surrounding these rarely encountered suffocation deaths is stressed.