The "SUpplémentation en VItamines et Minéraux AntioXydants" (SU.VI.MAX) study is a randomized double-blind, placebo-controlled, primary-prevention trial designed to test the efficacy of a daily supplementation with antioxidant vitamins and minerals at nutritional doses, in reducing several major health problems in industrialized countries, and especially the main causes of premature death (cancers and cardiovascular diseases). This 8-year cohort study started in 1994 in France; 13,535 eligible subjects (women aged 35 to 60, and men aged 45 to 60) were included in 1994 and will be followed up for 8 years. In this paper are described conditions and practical aspects for the realisation of the biological bank developped on the first sample (1994) and completed in 1996 and 1999. Biological material (buffy coat and plasma samples) are saved and stored at -196 degrees C, -80 degrees C and -20 degrees C for any further tests planned at later date (case-control studies and/or validation of new hypothesis).