Four color vision tests were used to assess color vision in 51 insulin-dependent diabetic patients and 41 normal controls. Right and left eyes of diabetic patients, selected because they had minimal retinopathy, had significantly more color vision defects than controls on Lanthony desaturated D-15, Farnsworth-Munsell 100-Hue, and chromagraph tests. The 100-Hue scores were significantly higher in both right and left eyes of diabetic patients than in controls. There were no significant associations between presence or absence of a color vision defect and age, sex, age at onset, duration of diabetes, or its metabolic control.