Polymorphic tetranucleotide microsatellites D3S1512, D3S1744, D3S1550, and D3S232 were used to study the association of chromosome region 3q21-q25 neighboring the angiotensin II receptor type 1 gene (AT2R1) with diabetic nephropathy (DN) in diabetes mellitus type 1 (DM1). Allele and genotype frequencies were compared for DM1 patients with (N = 39) or without (N = 62) DN. Fisher's exact test with Bonferroni's correction revealed significant differences in frequencies of two D3S2326 alleles, one D3S1512 allele, and one allele and one genotype of D3S1550. No significant difference was observed with D3S1744. Thus, region 3q21-q25 proved tightly associated with DN in ethnic Russians with DM1 from Moscow.