The presence or absence of islet cell autoantibodies is one of the most direct ways to distinguish between type 1 and 2 diabetic patients. The objective of the present study was to assess the prevalence of β-cell autoantibodies such as glutamic acid decarboxylase-65 antibodies (GADAs) and islet cell antibodies (ICA) among patients younger than 20 years of age with recently diagnosed diabetes in northwest of Iran. From 2006 to 2008, 163 patients were enrolled in this study. They were clinically classified into two groups: 136 with type 1 diabetes (T1D) and 27 with type 2 diabetes (T2D). Serum levels of GADAs, ICA and C-peptide were determined with enzyme linked immunosorbent assay (ELISA) kits. Fasting blood glucose and HbA1c levels were also determined. Chisquare test, independent t test and one-way analysis of variance were used for data analysis. The prevalence of GADAs in T1D patients was 33.1%, slightly lower than that of ICA 35.3%. Forty-eight patients (35.3%) with T1D were positive for ICA compared to only one (3.7%) in T2D patients. The overall occurrence of any autoantibody in T1D patients (60.3%) was significantly higher than that of T2D patients (18.5%) (P<0.001). There was a statistically different association with family history of diabetes among the autoantibody positive versus autoantibody negative patients with T1D (P<0.01). Our results confirmed the presence of GADAs and ICA in T1D patients in Iran, though roughly at a lower prevalence than that reported for Caucasian T1D patients, but very similar to other nonCaucasian ethnic populations.