In normoglycaemic subjects the haemoglobin glycosylation rate primarily depends on duration of erythrocyte life. Measurements of glycosylated haemoglobin therefore can be used to evaluate erythrocyte life. Indeed, glycosylated haemoglobin is significantly reduced (p less than 0.001) in patients with autoimmune haemolytic anaemia or Minkowski-Chauffard syndrome as compared with patients with non-haemolytic anaemia. In addition, there is a strong correlation (r = 0.92) in non-diabetic subjects between the level of glycosylated haemoglobin and the percentage of daily haemolysis, as determined by a method using 51 Cr-labelled antologous red cells.