INTRODUCTION In children with lymphoid tumors (LT) chemotherapy is the main treatment. It is known, that many chemotherapy drugs have toxic effects on the central nervous system and is a factor, that leads to significant cognitive impairment. Purpose: Search of neurophysiological, neurochemical, and psychological correlates of neurotoxicity in children with LT when programmed therapy. MATERIAL AND METHODS The study included 39 children (4-16 years) with LT, with acute lymphoblastic leukemia (ALL) - 25, with non-Hodgkin's lymphoma (NHL) - 14 who were treated according to the scheme m-BFM-90: for patients with ALL (mALL-BFM -90) and the NHL (mNHL - BFM-90). Investigated the EEG, REG, ECHO EG. In 12 children with LT in blood serum levels of middle molecules (MM) - indicator of general toxicity, N-acetylneuraminic acid (N-ANA) - indicator of neurotoxicity, malondialdehyde (MDA) - lipid peroxidation, tocopherol, retinol - indicators of antioxidant protection, level of catalase - as free radical oxida- lion; vanilmindalic acid levels (VMA) - as indicator of the state catecholaminergic system. Studies were performed before treatment, after induction of remission, after M-protocol, after the end of chemotherapy. In 23 children (11-16 years) with LT during chemotherapy, performed a comparison of EEG and the level of anxiety (Ch.D.Spilberger), <<strategy selection behavior>> (Thomas-Kilman). Control group - healthy children of the same age. RESULTS The main results obtained in the present study were that 1) Prior to initiation of treatment of children with LT had a EEG changes, indicating certain dysfunction of diencephalic structures of the brain, and probably due to metabolic disorders that affect the neurotransmitter metabolism. 2) Toxic effects of chemotherapy on the CNS program was shown on a range of indicators: according to EEC-increasing values of relative power in the band δ- and Θ-frequency range, lower α-activity, increase of relative power in the band betal,2; according to REG-hemodynamic compromise; increasing levels of neurochemical indicators N-ANA and the VMA. This was accompanied by behavior strategies <<adaptation>> and <<cooperation>>, are not peculiar to healthy peers. Identified individual predictors of neurotoxicity in the software of chemotherapy in children with LT.