Although heat-related illness and death are readily preventable, exposure to extreme temperatures causes at least 240 deaths during years with no heat wave. A heat wave is defined by the National Weather Service as > or = 3 consecutive days of temperatures > or = 90.0 F (> or = 32.2 C). In 1980, 1983, and 1988 (recent years with prolonged heat waves), 1700, 556, and 454 deaths, respectively, were attributed to heat. This report describes four instances of heat-related illness and death that occurred in the United States during 1994 and 1995 and summarizes risk factors for heat-related illness and death.