The non enzymatic glycation of circulating and structural proteins is the main biochemical consequence of the chronic hyperglycaemia of diabetes mellitus. Retinol binding protein (RPB) is a 21K plasma globulin with an half life of 12 hr; its non enzymatic glycation may reflect the variation of short term metabolic control (1-4 days). In this study two blood samples were withdrawn at four days interval from 24 non insulin dependent diabetic patients. Glycated RBP was measured by a two-site immunoradiometric assay and its variations correlated with the correspondent changes in the blood glucose level. A significant correlation (r = 0.471; p less than 0.02) was found between the time 4/time 0 ratios of glycated RBP and the time 4/time 0 ratios of blood glucose. These data suggest that measurement of non-enzymatically glycated RBP may be a useful tool to evaluate the short term state of non enzymatic glycation in diabetes.