Hypothermia, defined as a core body temperature of <95 degrees F (<35 degrees C), is preventable. Excessive exposure to cold temperatures leads to potentially fatal central nervous system depression, arrhythmias, and renal failure. Advanced age, chronic medical conditions, substance abuse, and homelessness are among risk factors for hypothermia-related death. This report describes three hypothermia-related deaths that occurred during 2005 and reviews CDC data on hypothermia-related deaths during 1999-2002 in the United States. Public health strategies should target U.S. populations at increased risk for exposure to excessive cold and recommend behavior modification (e.g., dressing warmly, modifying activity levels, or avoiding alcohol) to help reduce mortality and morbidity from hypothermia.