Reference values for the concentration of elements in whole blood for the UK population are presented together with estimates for concentrations in plasma and urine. The blood data, when compared with other values obtained for Belgium, Denmark and Italy, obtained through the EURO-Terviht programme of the European Union, together with data from other countries, indicate similar concentrations. The data provide a basis for identifying the expected levels for the non-occupational exposed population against which differences attributable to various states of well-being, morbidity and mortality can be evaluated. However, it is also apparent that significant differences do exist which are related to geography and diet. In order to consider these differences, further improvements in the determination of elements in human tissues and fluids are required. Particular attention should be paid to that proportion of an element in the environment which is bioavailable together with its toxicity.