Smoking is a leading cause of diseases associated with premature mortality in the United States; in 1985, these diseases accounted for an estimated 390,000 premature deaths. In this report, mortality data and estimates of smoking prevalence for 1988 are used to calculate smoking-attributable mortality (SAM), years of potential life lost (YPLL), and age-adjusted SAM and YPLL rates for the United States. Calculations were performed using Smoking-Attributable Mortality, Morbidity, and Economic Cost (SAMMEC II) software, which includes relative risk estimates for 22 adult (i.e., greater than or equal to 35 years of age) smoking-related diseases and relative risk estimates for four perinatal (i.e., less than 1 year of age) conditions. Age-, sex-, and race-specific mortality data for 1988 were obtained from CDC's National Center for Health Statistics. Data on burn deaths caused by cigarettes were obtained from the Federal Emergency Management Agency. The estimated number of deaths among nonsmokers from lung cancer attributable to passive smoking was obtained from a report of the National Academy of Sciences. Age-, sex-, and race-specific current and former smoking prevalence rates in 1988 for adults aged greater than or equal to 35 years and for women aged 18-44 years were estimated by linear extrapolation using National Health Interview Survey data for 1974-1987.