Hypothermia is considered a serious problem in big cities. In order to clarify factors contributing to urban hypothermia and death from cold, which will continue to be an issue in cities in the future, we analyzed autopsy reports recorded in the Tokyo Medical Examiner's Office from 1974 to 1983. In a total of 18,346 autopsy reports 157 deaths had been diagnosed as due to exposure to cold. Of these cases, the greatest number were males in their forties and fifties, and most of these were inebriated and/or homeless. Eighty-four percent of urban hypothermia cases occurred when the outdoor temperature was below 5 degrees C, and 50% of deaths from cold occurred when the outdoor temperature was between 0 degrees and 5 degrees C. There were no incidences of death from cold when the minimum outdoor temperature had remained above 16 degrees C. Seventy-four percent of deaths from cold occurred during the winter months of December, January and February, and most of the remaining deaths occurred in March and November. There were no deaths from cold from June to August. More than half of all deaths from cold occurred from 3.00 a.m. to 9.00 a.m., with the peak occurring at 5.00 a.m. A blood alcohol concentration of over 2.5 mg/ml had often been found in those in their forties and fifties who had died from hypothermia, and autopsy had often revealed disorders of the liver, digestive system, and circulatory system. Chronic lesions of the liver, probably due to alcoholism, were found in many cases; few cases showed no evidence of alcoholism and these were significantly different from the former group.