Objective: To study the penetration of mexidol through the blood-brain barrier into different brain compartments and cell mitochondria. Material and methods. The study was carried out on adult male Wistar rats using the drug mexidol ("Farmasoft" Russia). The penetration of mexidol into different compartments of the brain (the cortex, cerebellum, thalamus and medulla) and distribution between mitochondrial and cytoplasmic fractions of the cerebral cortex was studied. The concentration of mexidol in blood plasma and brain tissues was measured using HPLC. Results and Conclusion. Mexidol penetrated through the blood-brain barrier into brain compartments of rats with the maximal accumulation in the cortex. In the brain cortex cells, mexidol was identified in the cytoplasmic and mitochondrial fractions.