Background: Increased carotid intima-media thickness (CIMT) is considered as a marker for early detection of atherosclerotic changes in the arterial walls. The purpose of this study was to assess CIMT in type 1 diabetic patients compared to controls. Materials and Methods: A case-control study was performed on 34 patients with type 1diabetes mellitus and 33 healthy people in Kashan during 2013-2014. The inclusion criterion was the diabetes history more than one year and the exclusion criteria were the use of antihypertensive or lipid reducing drugs, smoking, family history of cardiovascular disease, any complications of diabetes and any chronic disease. The weight, height, blood pressure and CIMT of the patients were measured. Moreover, laboratory tests including fast blood sugar, Hb A1c and lipid tests were performed.Results: Sixty-seven subjects (34 type 1 diabetes patients and 33 healthy controls) were evaluated. The mean history of diabetes mellitus was 76.03±51.44 months. The mean age of the healthy subjects was 15.35±5.73 years and for the patients 15.25±7.94 years. Mean CIMT in healthy subjects was 0.439±0.06 mm and in patients 0.478±0.05 mm (P=0.005). Moreover, maximum CIMT was higher in the patients than in the controls (P=0.01). The multiple linear regression showed that CIMT was about 0.012 units higher in diabetic patients than in controls, and also CIMT was increased 0.012 units per one unit increase in HbA1c values.Conclusion: The mean CIMT in patients with type 1diabetes was higher than in the controls and positively correlated with the history of diabetes, while it does not correlate with the lipid profiles, blood pressure and body mass index