Data from this article, as in previous reports,1 are drawn principally from Monthly Vital Statistics Report, published by the National Center for Health Statistics (NCHS).2-6 The international data come from the Demographic Yearbook7 and the quarterly Population and Vital Statistics Report,8 both published by the Statistical Office of the United Nations, which has also been kind enough to provide directly more recent data. Except for mortality data by cause and age, which are based on a 10% sample, all the US data for 1986 are estimates by place of occurrence, based upon a count of certificates received in state offices between two dates, 1 month apart, regardless of when the event occurred. Experience has shown that for the country as a whole the estimates, with few exceptions, are close to the subsequent final figures. There are considerable variations in some states, however, particularly in comparing provisional figures by place of occurrence and final data by place of residence. State information should be interpreted cautiously. Careful attention should be paid to the denominator when studying rates presented in this article. For overall rates, like the birth rate or death rate, the standard denominator is 1,000 total population. In instances where more refined analysis is possible, the denominator may be 100,000 and the character of the population specified. The particular denominator is indicated in the table or in the context.