© 2018The objective of this study was to examine the association between ADHD and G1287A polymorphism in the NET1 gene, C1291G polymorphism in the ADRA2A gene on the adrenergic pathway and Gly143Glu polymorphism in the CES1 gene on the metabolic pathway, and their clinical effects. The study population included 114 children with ADHD and 83 healthy controls. 103 patients are followed for 6 months, their scale points are recorded and side effects are questioned in each interview. Every patient in both control and ADHD group are found to have GG genotype when Gly143Glu polymorphism in the CES1 gene is examined, thus we came to a conclusion that Turkish population is homozygote in the mentioned polymorphism. No significant association between NET1 gene G1287A polymorphism genotypes and ADHD was found. It was found that ADRA2A C1291G polymorphism C allele and CC genotype is a risk factor for ADHD (p = 0.003, OR: 2.17, CI: 12.8–37.0) and the risk is higher in males (p = 0.013, OR: 2.43, CI: 12.0–49.5). There was no significant relation between ADRA2A C1291G polymorphism and clinical parameters but it was found that individuals with NET1 G1287A polymorphism AA genotype have less concurrent Oppositional Defiant Disorder diagnosis (18.8% vs. 81.2%, p = 0.039), their initial CTRS-attention deficit points are higher (17.47 ± 3.73 vs.16.15 ± 4.58, p = 0.045). In conclusion, our study showed that the ADRA2A C1291G polymorphism C allele and CC genotype is associated with ADHD. NET1 G1287A polymorphism AA genotype is mainly associated with attention deficit cluster.