Erythrocyte microrheology changes were measured using cation-osmotic haemolysis (COH) in healthy rats and rats after 6 and 12 months of cadmium ingestion. Using COH properties of two membrane constituents, spectrine membrane skeleton and membrane bilayer, were studied. COH in rats after 6 months of cadmium ingestion was significantly lower only in the area with lower ionic strength. However, longer intake of cadmium (12 months) induced decrease of COH in both areas, with lower and also with higher ionic strength. The relation between cation-osmotic haemolysis and erythrocyte deformability is being discussed. (C) 2000 Elsevier Science B.V. All rights reserved.