Patients suffering from manganese encephalopathy, which develops while taking surrogate drugs, suffer from pronounced subcortical pseudobulbar syndrome, pyramidal insufficiency and a complex of autonomic disorders. The most pronounced of them are disorders of motor functions. The work is devoted to the study of the bioelectrical activity of the brain of patients with manganese encephalopathy in order to develop an EEG-criterion for diagnosing this disease. The subjects underwent EEG recording using a 16-channel electroencephalograph "NeuroCom standart" (KhAI-Medika, Ukraine) in accordance with the international recording system "10-20". The following were analyzed: the power of the signals of the main rhythms of the background EEG, the relative characteristics of the power of the signals of the main EEG rhythms – the activation coefficient of the cortex, the activation coefficient of the sub cortex, the indices of interhemispheric asymmetries in terms of the power of bioelectric signals in bilaterally synchronous points of the head. It was found that in patients with manganese encephalopathy both the cortical activation coefficients and the sub cortex activation coefficients had values that can be observed in patients with аnother diseases. In turn, such indicators as interhemispheric asymmetry in the power of signals of individual rhythms and interhemispheric asymmetry in the total power of signals at bilaterally synchronous points of the head in patients with manganese encephalopathy had values that significantly differed from those in patients with other types of pathology. So, with indicators of 16-18 interhemispheric asymmetries in healthy people and 9-25 in patients in coma, in patients with manganese encephalopathy, it was observed: in one patient – 12 interhemispheric asymmetries, in the other of the patients – 9, 7, 3 and 2 interhemispheric asymmetries in signal power of individual rhythms at bilaterally synchronous points of the head. The reason for such a pronounced smoothing of interhemispheric asymmetries in patients with manganese encephalopathy, obviously, may be those destructive changes in the subcortical parts of the GM that are present in this group of patients.