"The Norwegian Women and Cancer Study" was started in 1991/92 when random samples of Norwegian women from the Central Person register in Statistics Norway were invited to participate in a prospective study based on linkage to the Norwegian Cancer Registry and the death register. At the end of 1997 altogether 102,540 women were enrolled. The questionnaires focused partly on hormonal related information including oral contraceptives, dietary habits with focus on fish consumption, sun habits and other life s tyle factors like place of residence, smoking etc. During 1998-2000 altogether 67,000 women will be invited for a second time. As part of the EPIC study this project will complete the calibration study with 2000 24-hours recall in June and start blood sam pling. The project wants to complete the second mailing to the last 35,000 women, including a sample of blood from 5,000. At present the analysis has started with the joint Norwegian-Swedish cohort of 106,000 women on the relationship between oral contrac eptive use, physical activity and diet in relation to breast cancer, and the cross-sectional analysis of 35,000 24-hours recall for the calibration study.