SUMMARY. We compared the urinary excretion of albumin, transferrin, N-acetyl--D-glucosaminidase and o-l-microglcbulin in 78 Type 1 (insulin-dependent) diabetic patients: 39 with retinopathy and 39 without. The two groups were matched for age, sex and duration of diabetes. The patients with retinopathy had increased excretion (median and range) of albumin [1'7 (0' 3-399·1) versus 1·0 (0' 3-116'6) mg/mmol creatinine, P<0'05j, transferrin [114'2 (4'1-37126'2) versus 33·4 (1'0-4176'7) JLg/mmol creatinine, P< 0'01] and N-acetyl-~-D-glucosaminidase [23' 8 (1'1-119'1) versus 15·0 (0'1-65 '1) JLmol/h/mmol creatinine, P