Leprosy is a chronic infectious disease of M. leprae that causes damage to the skin and nerves. Indonesia is one of the countries which is the endemic areas of leprosy, the prevalence of leprosy continues to increase. The immune response not only determines the type of leprosy that will manifest to individual, but also determines an individual's susceptibility to leprosy. One of the cytokines that play an important role in the pathogenesis of leprosy is interleukin-10 (IL-10), which works on active macrophages to end the response to microbes and return the system to rest when the microbes are destroyed. Increased regulation of IL-10 can affect the decrease in macrophage activity in killing bacteria. Polymorphism of -819 is thought to influence the expression of IL-10 genes. This study aims to identify the polymorphism of the -819 of the interleukin-10 promoter gene in leprosy patients treated at RSUP dr. Mohammad Hoesin Palembang. This research is an observational descriptive study with cross sectional design. Polymorphism of the -819 of the interleukin-10 promoter gene was measured by the PCR-RFLP method, electrophoresis, and visualized in UV light. From this study, the frequency distribution of TT genotypes is 42%, CT is 44%, and CC is 14%. The frequency distribution of T allele is 32% and C allele is 18%. Wild type genotype description is more common in leprosy sufferers (80%).