Smoking status and sociodemographic characteristics were recorded for 23,572 white women 25-74 years of age in a private census of Washington County, Maryland, done in 1963. Deaths from all causes, from total and sudden arteriosclerotic heart disease, and with stroke were recorded for the next 12 years. Smoking-specific mortality rates for women aged 25-44, 45-64, and 65-74 years at entry were calculated after adjustment for the effects of marital status, education, housing quality, and frequency of church attendance. Among women in the 65-74-year age group, smoking was not related to mortality. Among women in the two younger age groups, the risks of dying from any cause and from arteriosclerotic heart disease (total and sudden) were positively associated with cigarette smoking. For all arteriosclerotic heart disease deaths, the relative risks associated with smoking more than 20 cigarettes a day were 3.6 and 2.2 for women aged 25-44 and 45-64, respectively; for sudden deaths from arteriosclerotic heart disease, the relative risks were 6.5 and 2.7. The risk of dying with stroke was not associated with cigarette smoking.