Contrast sensitivity measurements were obtained from 66 patients with Insulin Dependent Diabetes Mellitus (IDDM) and no visible diabetic retinopathy (Group A, n = 30 prepubescent and pubescent subjects; Group B, n = 36 postpubescent subjects). Contrast thresholds were determined for stationary and 6.87 Hz phase-alternating gratings at eight spatial frequencies from 0.18 to 15.7 c/deg. Data from each group of diabetic patients was compared with data from puberty-matched normal subjects. Mean value of the last four determinations of glycohemoglobin Alc (HbAlc) was used as a index of glycemic control. We found that patients with IDDM and no retinopathy had normal contrast sensitivity and that contrast thresholds were not significantly related to sexual maturity, duration of diabetes and glycemic control.