An analysis is made of the mortality trends over the period 1968 to 1977 indicated by two types of cause-specific mortality data. The first type of data is "underlying cause" of death data--the data heretofore used in national vital statistics reports on cause-specific mortality. The second type of data is "multiple cause" data which contain a listing of all medical conditions recorded on the death certificate. A comparison of trends in the two types of data yields useful insights on mortality declines over the study period for two reasons. First, these declines were largely due to a reduction in the mortality rates of circulatory diseases. Second, the multiple cause data contain considerably more information than the underlying cause data on the role of circulatory diseases, and many other chronic diseases, in causing death. This additional information is especially useful in examining mortality patterns among the elderly, where the prevalence at death of chronic degenerative diseases is high.