Type 1 diabetes mellitus formerly called juvenile diabetes, is an organ specific T-cell mediated autoimmune disease characterized by the progressive loss of function of the insulin producing beta-cells of the islets of Langerhans. Cytotoxic T lymphocyte-associated antigen 4 gene (CTLA-4) has been proposed as a candidate gene for conferring susceptibility to autoimmunity. Association of CTLA-4 gene polymorphism is well established in autoimmune endocrinopathies across world population. The present study was conducted to investigate the association of CTLA-4 exon 1 49A/G polymorphism with TIDM in Madurai, a city in Southern India. Fifty three clinically proven T1DM patients and 53 control subjects with no history of autoimmune disease were recruited for the study. Genomic DNA was extracted from peripheral blood. CTLA-4 exon 1 49 A/G polymorphism was assessed using PCR-RFLP methods. Our findings revealed a significant association of CTLA-4 exon 1 49 A/G polymorphism with T1DM in Madurai population.