Interleukin-18 (IL-18) gene promoter polymorphism is known as a genetic risk factor for child type 1 diabetes mellitus development. To test the role of IL-18 gene polymorphism in predisposition to adult type 1 diabetes (T1DM) and latent autoimmune diabetes in adults (LADA), we analysed SNPs at position -607 (C/A) and -137 (G/C) in the promoter region of IL-18 gene by sequence-specific PCR in 49 T1DM, 66 LADA patients and 139 healthy controls. We found differences in allele, genotype or haplotype distribution in tested patients when compared to frequencies found in control group but these differences did not reach statistical significance. However, there was a difference in -607 (C/A) allele and genotype distribution found in LADA and T1DM patients that reached statistical significance. These results suggest that the IL-18 gene promoter polymorphisms are not associated with adult type 1 diabetes or LADA susceptibility, and according to our findings genes involved in onset and progression of LADA and T1DM are probably different.