Ashford, J. R. (Dept. Mathematical Statistics and Operational Research, University of Exeter, Streatham Court, Rennes Drive, Exeter EX4 4PU, England) and Lawrence, P. A. Aspects of the epidemiology of suicide in England and Wales. International Journal of Epidemiology 1976, 5: 133–144. This paper is concerned with the variations in suicide rates in the 161–170 local authorities in England and Wales during the 11 -year period 1961–71. Analysis of the overall secular trends shows that the rates for both males and females reached a peak in 1963 and subsequently declined at a steady rate. Virtually the whole of this reduction is associated with the fall in the number of poisonings by domestic gas. Suicide rates were about 50 per cent higher in males than in females and tended to increase with increasing age and, in general, were higher in the county boroughs than in the (more rural) county authorities. There is a marked variation in terms of geographical area, with the highest rates being reported in the London and South-East Region and the lowest rates in the South-East Wales and Northern Regions. There are also systematic differences between the various conurbations, with the highest rates in London and South-East Lancashire and the lowest in Merseyside and the West Midlands. The variations between individual local authorities are then considered and it is shown that as much as 99 per cent of the total variation can be explained in terms of a small number of variables which represent the general characteristics of the local authority and the population. The most important of these variables is the proportion of single-person households, which accounts for about three-quarters of the variation in the male suicide rates and more than half of the variation in female suicide rates. The significance of these results is discussed, with particular reference to the effect of the detoxification of the domestic gas supply during the period of study.