The present study was undertaken to determine the clinical usefulness of fructosamine estimations in monitoring the short term changing in metabolic control in 5 newly diagnosed type 1 diabetic children (3 boys, 2 girls, aged 3-13 years). Mean glycaemic values, HbAlc (normal range: 4.77 +/- 0.67%), fructosamine (normal range: 2.65 +/- 0.65 mmol/l) were determined at the admission and after 1, 2, 3, 4 weeks. Normoglycaemia was achieved within 1 week (mean values: 232 +/- 107 mg% at admission; 98 +/- 39 mg% after 1 week of insulin therapy), HbAlc slightly decreased from 12 +/- 0.71 at admission to 9.90 +/- 1.81 after 4 weeks, but not reached normal values. Fructosamine decreased from 5.49 mmol/l to near normal values (3.02 +/- 0.67) after 4 weeks. The validity of the method was confirmed by the comparison of HbAlc and fructosamine in 22 stable long-standing diabetic children (r = 0.77, p less than 0.01). Compared with HbAlc, fructosamine appeared more useful in monitoring short term (3 weeks) changes in metabolic control. Additional advantages were lower cost and technical simplicity of measurement.