This paper describes patterns and trends in COPD morbidity and mortality based on data from several data systems of the National Center for Health Statistics (NCHS), as follows: mortality data from the National Vital Statistics System; and morbidity data from the National Health Interview Survey, the National Hospital Discharge Survey, and the National Ambulatory Medical Care Survey. The paper focuses on the period 1979 to 1985 and the age groups 55 years old and over. old and over. Data are also presented separately for men and women. In addition to presenting rates for prevalence, hospital discharges, office visits, and deaths on a population basis, the paper also presents rates and analyses on a per case basis, using a "pseudo-natural history model." This paper also describes some of the methodological issues associated with analyzing comparative data from several NCHS data systems.