Previous reports of contrast sensitivity in diabetic patients have shown conflicting results. We evaluated contrast sensitivity using Cambridge low-contrast sensitivity charts in 22 diabetic patients (22 eyes without retinopathy and 16 eyes with background retinopathy on fluorescein angiography) and 10 control subjects (20 eyes) matched for age and sex. The mean contrast threshold values at a spatial frequency of 4 cycles/degree were 0.46%, 0.60% and 0.43% in the three groups of eyes respectively. Contrast sensitivity was significantly lower in the diabetic eyes with retinopathy than in the normal eyes (p = 0.011) or the diabetic eyes without retinopathy (p = 0.033). This test may be of value in screening diabetic patients for retinopathy in primary care facilities.