Studies of occupational exposures have been a fruitful area of research for identifying carcinogens. Some of the early observations, such as increased risk of breast cancer among nuns and bone cancer among radium dial workers, were made among women. Recent research on cancer among women has shown increased risks of cancer in many industries and occupations. Estimates that 1% of cancer among women is attributable to occupation are based on research conducted mainly in the 1970s among men in developed countries. These studies do not reflect the dramatic changes in the participation of women in the workplace or the patterns of employment of women in developing countries. The proportion of women in the paid workforce, the amounts and types of unpaid labor, the distribution of women by economy sector, the scale of the workplaces, the allowable exposure levels in the workplace, and implementation of controls have changed over time and vary internationally. Occupational cancer researchers need to expand their focus on women, increase activities in developing countries, include newly created industries, use sophisticated exposure assessment methods, and, where appropriate, incorporate molecular epidemiologic techniques to discover new occupational carcinogens and to identify where better control measures are needed.