Serum levels of biochemical parameters were measured using commercially available electrochemiluminescence immunoassay and enzyme-linked immunosorbent assay kits.<h4>Results</h4>Compared with the healthy control group, the ADHD group exhibited significantly higher serum levels of BDNF, GDNF, VEGF, ACTH, and cortisol, whereas NT-3 levels did not differ between the groups. This evidence concerns the gene GDNF and attention deficit-hyperactivity disorder.