Most studies of occupational cancer have included only male employees. In Denmark more than 40% of the labour force have been women since the 1970s and a large proportion of Danish women may have had occupational exposures, including exposures to carcinogens. In a register linkage study we investigated cancer incidence in a cohort of 1.4 million women, categorized by occupation in the 1970 census. Professionals, salaried employees and unskilled workers all had a slightly increased overall cancer risk. The risk of breast cancer was significantly increased in several groups of professionals such as lawyers, medical doctors, dentists and physiotherapists, nurses and clerks, but in only 2 groups of blue-collar workers: skilled tobacco workers and bookbinders. Ovarian cancer incidence was significantly elevated among clerks, while travelling saleswomen, furriers, hairdressers, nurses, and clerks had a significant excess of uterine corpus cancer. Uterine cervix cancer was almost exclusively elevated in a variety of unskilled occupations. Women should be included in studies of occupation and cancer. Although occupational hazards cannot be excluded for some associations found in this study, reproductive and lifestyle factors may also influence cancer risk and need to be considered in studies of occupation and cancer in women.