Currently there are no available biological markers that have been satisfactorily validated clinically as 'intermediate end-points' for evaluation of the impact of diet on cancer. Therefore, there is high scientific value in banking biological specimens for future use in the Malmö Diet and Cancer Study. The banking procedures we have developed are adequate for assessing factors that estimate dietary intake (e.g. vitamins, lipids or micronutrients) as well as non-dietary variables (e.g. immunologic and ecogenetic factors of biologically effective doses of xenobiotic exposures) that may regulate the biological expression of dietary variables. This approach is further justified by state-of-the-art technology that includes assessment of the concept of gene-environment interactions. Purified viable mononuclear leucocytes, granulocytes, erythrocytes, plasma and serum are being stored from each individual entering the study under the guidelines of a strict quality control programme. Storage of tumour/normal tissues from incident cancer cases are also being stored and quality controlled. It is hoped that these banking procedures will encourage a high activity in biomarker development in the future.