Localized aggressive periodontitis (LAgP) is a complex multifactorial periodontal disease to which genetic factors are thought to predispose individuals. Interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α) are potent immunomodulators and proinflammatory cytokines that have been implicated in the pathogenesis of autoimmune and infectious diseases and proposed to be risk factors for LAgP. Our aim was to investigate IL-1 α ⁺⁴⁸⁴⁵, IL-1 β ⁺³⁹⁵⁴, and TNF-α ^-308 gene polymorphisms in Turkish LAgP patients. We genotyped 31 LAgP patients and 31 healthy controls for IL-1α⁺⁴⁸⁴⁵, IL-1β⁺³⁹⁵⁴, and TNF-α^-308 using standard PCR amplification followed by restriction enzyme digestion and gel electrophoresis. Higher prevalence of heterozygosity for IL-1α⁺⁴⁸⁴⁵ was found in cases (65%) when compared to controls (35%) (P < 0.05). While homozygous allele 1 of IL-1β⁺³⁹⁵⁴ was the most frequent genotype in cases (62%), no controls were homozygous for this allele (P < 0.001). Homozygous allele 1 was the most common TNF-α genotype in both groups, however no significant difference in TNF-α genotypes was found between groups. In conclusion, in this Turkish population, susceptibility to LAgP is increased by heterozygosity for allele 1 of IL-1α⁺⁴⁸⁴⁵ or homozygosity for allele 1 of IL-1β⁺³⁹⁵⁴. Moreover, IL-1 gene polymorphisms appear to have a role in susceptibility to LAgP, and the above-mentioned genotypes could be an important risk factor for LAgP in the Turkish population. (J. Oral Sci. 50, 151-159, 2008)