During this century, Catholic sisters have remained constant in many life-style characteristics such as smoking and reproduction (Catholic sisters are nonsmoking and nulliparous). It is therefore of interest to compare trends in the health of elderly Catholic sisters to those in the general population. In this study, mortality rates at ages 50 to 84 years in a population of 2,573 Catholic sisters were compared to those in the general population during the years 1965 to 1989. The Catholic sisters had a mortality advantage that increased dramatically over calendar time, and from early to more recent birth cohorts. This coincided with increases in smoking by U.S. women, while during the same time period the Catholic sisters had very low rates of mortality from smoking-related diseases. The Catholic sisters had high rates of mortality from cancers of the breast and reproductive organs, suggesting an effect of nulliparity manifested in older women.