CO inhalation is one of the leading methods of suicide in the United States. A sharp increase in suicide by inhaling the CO produced from burning charcoal has been reported in parts of Asia; however, the incidence of this method has not been determined in a U.S. population. During the period 1996-2009, the current study identified 158 cases of suicide by CO poisoning, with 125 because of automotive exhaust, 26 because of charcoal burning, and 7 from other CO sources. While historical U.S. data indicate greater than 99 percent of CO suicides in the United States occurring by automobile exhaust inhalation, in the most recent years analyzed, c. 40 percent of CO-related suicides in King County, WA, were because of charcoal burning, indicating a possible shift in suicide trends that warrants further scrutiny in additional populations. (Published Abstract)