Prior to the 1920s, lung cancer was a rare disease. However, the current increase in lung cancer appears to parallel the increase in smoking for both men and women with a 30- to 50-year delay. National lung cancer deaths continue to rise, with over 168,000 total deaths estimated in 1992. Women are now showing higher percentage increases in lung cancer than men from active smoking. The data from the Erie County Study on Smoking and Health (ECSSH), a population study, were used to measure the effects of both active and passive smoking on women's lung cancer mortality. The three major categories of exposure (no known or minimal exposure, passive smoking exposed, and active smoking) were used in the analyses. The results from the population data in Erie County, PA, were based on 528 nonexposed nonsmoking women, 3138 exposed nonsmoking women, and 1747 smoking women. Deaths due to lung cancer as a percentage of total deaths excluding traumatic deaths were 0.2% for the nonexposed nonsmoking women, 0.9% for the exposed nonsmoking women, and 8.0% for women who smoked. The data showed that women smokers died of lung cancer at a rate 9 times greater than exposed nonsmokers and 42 times greater than nonexposed nonsmokers.