Carbon monoxide (CO) gas is an environmental hazard, and unintentional CO poisonings have occurred in multiple settings, including residences, motor vehicles, and workplaces. In 1993, exposure to CO produced by a malfunctioning natural gas furnace in a Suffield, Connecticut, home resulted in the deaths of three children and hospitalization of four other family members. Publicity resulting from this and other CO poisoning incidents prompted concern that gas furnaces have been a primary cause of residential CO poisonings in Connecticut. To determine the sources of residential CO poisonings in Connecticut, the Connecticut Department of Public Health (CDPH) surveyed persons with cases of CO poisoning during November 1993-March 1994. This report presents the survey findings.