A study of fire deaths in the Glasgow area has been extended to the rest of the United Kingdom in order to assess the applicability of the conclusions reached in the Glasgow study to the whole country. With assistance from pathologists in a number of other areas, 71 cases were included in the study, covering both pathology and toxicology of the deaths where possible. In both the Glasgow and UK studies, most of the fire deaths occurred in dwelling-house fires. These and other demographic characteristics were in agreement with national fire statistics. The principal features of pathology in this study were burns (79 per cent of cases), respiratory system injury (72 per cent of cases) and soot deposition in the respiratory tract (96 per cent of cases), and these reflected a similar incidence in the Glasgow study. Carbon monoxide was considered to be the cause of death in 51 per cent of the deaths in this study and to be implicated in the death of 37 per cent of the other cases (54 per cent and 31 per cent respectively in Glasgow). Cyanide was estimated to be a significant factor in 33 per cent of the deaths in the UK study (24 per cent in Glasgow). Alcoholic intoxication was found to be a significant additional factor in Glasgow but was much less prominent in the other areas of the UK. It is concluded that, with the exception of alcohol, the results of the Glasgow study are valid for the UK as a whole.