The content of vitamins in milk is important for the human consumer, the calf, the health of the cow, as well as for the quality of the dairy product. There is a lack of knowledge about the vitamin and selenium content in organic milk in Sweden, especially in comparison to conventional milk, although there are studies indicating that there are differences. In this study, 40 herds, 20 organic and 20 conventional, was visited during the autumn 2005 and will be visited during spring 2006, where samples from the bulk tank are taken. The farmers were also instructed to take samples in the period between the visits, and to store the samples frozen until pick-up. The contents of vitamin A and E and selenium in the milk samples will be analysed and differences between farms will be investigated using multivariable mixed linear regression models. Effects of other herd characteristics such as herd size, breed, milk production, as well as effects of season, will also be studied.