MAGNE-B6 was used for the therapy of a group of 31 children aged from 6 to 12 with attention deficiency and hyperactivity syndrome. The control group included 20 children with similar manifestations of the same pathology, which received a polyvitamin complex. The efficacy of therapy was assessed in the 30th day with the aid of a complex clinical-neuropsychological and biochemical investigations. It was established that the administration of MAGNE-B6 led to improvements in the behavior, decreased the level of anxiety and aggression, improved both large- and small-scale mobility, decreased the level of synkinesis, increased the characteristics of attention, corrected the magnesium homeostasis, and favored normalization of the blood electrolytes. Reliable differences (p < 0.01 or 0.001) between the test and control groups in the degree of expression of the indicated disorders were observed.