Smoking prevalence is lower among women than men in most countries, yet there are about 200 million women in the world who smoke, and in addition, there are millions more who chew tobacco. Approximately 22% of women in developed countries and 9% of women in developing countries smoke, but because most women live in developing countries, there are numerically more women smokers in developing countries. Unless effective, comprehensive and sustained initiatives are implemented to reduce smoking uptake among young women and increase cessation rates among women, the prevalence of female smoking in developed and developing countries is likely to rise to 20% by 2025. This would mean that by 2025 there could be 532 million women smokers. Even if prevalence levels do not rise, the number of women who smoke will increase because the population of women in the world is predicted to rise from the current 3.1 billion to 4.2 billion by 2025. Thus, while the epidemic of tobacco use among men is in slow decline, the epidemic among women will not reach its peak until well into the 21st century. This will have enormous consequences not only for women's health and economic wellbeing but also for that of their families. The health effects of smoking for women are more serious than for men. In addition to the general health problems common to both genders, women face additional hazards in pregnancy, female-specific cancers such as cancer of the cervix, and exposure to passive smoking. In Asia, although there are currently lower levels of tobacco use among women, smoking among girls is already on the rise in some areas. The spending power of girls and women is increasing so that cigarettes are becoming more affordable. The social and cultural constraints that previously prevented many women from smoking are weakening; and women-specific health education and quitting programmes are rare. Furthermore, evidence suggests that women find it harder to quit smoking. The tobacco companies are targeting women by marketing light, mild, and menthol cigarettes, and introducing advertising directed at women. The greatest challenge and opportunity in primary preventive health in Asia and in other developing areas is to avert the predicted rise in smoking among women.