Genetic variations of the antioxidant enzymes may influence the susceptibility to oxidative stress and consequently the development and progression of diabetic complications. The aim of the current study was to test the association between the −262C/T polymorphism in the catalase gene promoter and carotid atherosclerosis in Slovenian patients with type 2 diabetes. Two-hundred and eighty six diabetics and 150 healthy controls were enrolled in the study. Carotid atherosclerosis was quantified ultrasonographiocally by carotid intima-media thickness (CITM), plaque score and plaque type. Genotypes were determined using the real-time PCR. Fibrinogen concentration showed a borderline statistically significant difference due to catalase genotypes (p=0,05). No difference in clinical characteristics, CIMT, plaque stability or plaque score was observed. Logistic regression model adjusted for age, gender, smoking, BMI, lipid parameters and duration of hypertension and diabetes showed significant association of T allele and lower risk for higher plaque score (OR=0,25; p=0,025). No association with CIMT>1mm and unstable plaques was observed. T allele of −262C/T is associated with lower risk for higher plaque score but it did not affect clinical parameters, CIMT and plaque stability. Whether this polymorphism can be used as a genetic marker for advanced carotid atherosclerosis in diabetic patients needs to be evaluated in the future.