In 1987 a mixture for exchange transfusion was introduced in the Netherlands. It was composed of citrated red cells, heparinized plasma and third-party platelets if necessary. Selected biochemical and haematological properties of this mixture were compared to fresh heparinized whole blood, which was at that time the blood product of choice for exchange transfusion. The parameters of the mixture were less physiological than fresh heparinized whole blood. In addition, retrospective analysis of the same parameters was performed upon 149 blood samples from newborn infants who had undergone exchange transfusion. The bilirubin decreasing capacity of the mixture was adequate. Most other parameters did not change considerably and remained within the physiological range. This mixture may be an adequate product for exchange transfusion. However, to be certain of its safety and suitability, several other biochemical and haematological aspects must be studied in addition to the immunological and infectious risks.