Carbon monoxide (CO) is formed wherever incomplete combustion of carbonaceous products occurs.(1) CO is the leading cause of poisoning in the United States, and common sources of CO poisoning include housefires, automobile exhaust, water heaters, kerosene space heaters, and furnaces.(2) Stoves used for cooking and heating during outdoor activities also produce significant amounts of CO. Mountain climbers have been reported to succumb to fumes generated by small cook stoves.(3) The aim of this study was to investigate if burning a cooking stove inside a tent is a potential health hazard. Seven healthy male volunteers used a cooking stove inside a small tent for 120 minutes. CO levels in the ambient tent air were measured in addition to hearth rate (HR) and pulse oximetry (SpO2). Venous blood samples were obtained every 15 minutes for measurement of carboxyhemoglobin (COHb). After 2 hours, all the subjects had significant CO levels in their blood (mean COHb = 21.5%). Mean SpO2, also fell from 98% to 95.3% (P <.05), whereas mean HR increased from 63 to 90 beats/min (P <.05). Kerosene camping stoves do produce CO when burned in a small tent. The concentration is high enough to cause significant COHb levels in venous blood after 120 minutes' stay in the tent.