|Attention-deficit hyperactivity disorder (ADHD) is a common neurodevelopmental polygenetic heritable disorder that includes inattention, excessive motor activity, impulsivity and distractibility. In the past few years, interest in the molecular genetics of ADHD has grown enormously, with many groups searching for susceptibility genes. Dopaminergic genes have been prime candidates in the search for the genetic factors underlying novelty seeking because of the central role that dopamine plays in the brain's reward system. However, the findings are not conclusive and other new polymorphisms in different gene backgrounds are investigated. We have investigated whether there is an association between genes involving nervous system - cytokines, including IL-2, IL-6, and tumor necrosis factor-alpha (TNF-alpha). It is known that proinflammatory pleiotropic cytokines such as interleukin-6 (IL-6) are expressed in the central nervous system (CNS) during disease conditions and affect several brain functions including memory and learning. Genetic variation in the promoter region of the gene encoding the cytokine IL-6; -174 C/C polymorphism may encode enhanced production of IL-6. Our objective was to determine whether the CC genotype is associated with ADHD. In our association study, we studied the difference in genotype and allelic frequencies 174 polymorphism of IL-6 gene between hyperkinetic boys and boys in control group. We isolated genomic DNA from buccal tissue or blood sample collected from each individual. DNA was extracted by commercial kits UltraClean Tissue DNA or BloodSpin kit (Mobio, USA). Polymerase Chain Reaction (PCR) was used for determination of genotypes. PCR products were digested with restriction enzyme Taq I (MBI Fermentas) and subsequent electrophoresed on 2% agarose gel (Eliphore). The X2 test and Fischer-exact test were performed to assess the significance or non-significance association between studied groups of boys. We found the association between 174 polymorphism of IL-6 gene and ADHD. The allele C was observed frequently in ADHD group than in control group. These findings highlight the need for further investigations of cytokines genes, in additional independent ADHD samples, in the future.