Biochemical indicators of dietary nutrient intake are called biomarkers. They are used in clinical settings to assess deficiency or excess of nutrients like iron, iodine, vitamin C and D. In nutritional epidemiology biomarkers are used to classify subjects according to their nutrient intake from foods and relate it to a disease. Biomarkers can be classified into poor, intermediate and good according to several criteria. Many factors influence the relationship between nutrient intake and tissue concentration like homeostasis, metabolism, age, gender and nutrient interactions. An important factor to be taken into account is also whether the biomarker reflects short or long term intake. By the initiative of the Working Group on Diet and Nutrition (NKE) an expert seminar with the topic "Biomarkers of Nutritional Intake" was arranged on the17-18th September 2004 in Helsinki. Foremost experts on biomarkers from the United Kingdom and the Nordic Countries presented their views on the state of the art with special emphasis on Nordic conditions. This report contains extended abstracts of topics which were presented at the seminar. The topics ranged from nutritional epidemiology to clinical interventions to validation of new biomarkers.