Susceptibility to and development of periodontal disease have been associated with psychological conditions. Previous studies have associated the presence of polymorphism in the promoter region of the serotonin transporter with several behavioral traits and psychological conditions such as depression, anxiety, and stress. The short allele S has a reduced transcriptional efficiency and is associated with lowered serotonin expression and uptake. The purpose of the present study was to investigate the association between 5-HTTLPR polymorphism and aggressive periodontitis in a sample of Brazilian individuals. This study involved 61 individuals affected by aggressive periodontitis and 71 without periodontitis. Genomic DNA was obtained from oral swabs, amplified by polymerase chain reaction (PCR), and genotyped at 5-HTTLPR. The Chi-square test and multivariate logistic regression were used for statistical analysis. The aggressive periodontitis group displayed a significantly higher occurrence of genotype SS (P < 0.01) and of allele S (P < 0.01). After adjustment for gender and age, it was observed that genotype SS occurred 8 times more frequently in this group. Our findings suggest that 5-HTTLPR polymorphism might be associated with aggressive periodontitis in the Brazilian population.