Effects of the psychostimulants D-amphetamine and sydnocarb on the locomotor activity and c-Fos protein expression in the brain of C57BL and BALB/c mice was studied. The drugs significantly increase the locomotor activity and the level of c-Fos protein in the brain structures of both lines. The effect of D-amphetamine with respect to the locomotor activity was more pronounced in C57BL mice, which correlates with a higher level of the c-Fos expression in the secondary motor cortex. At the same time syndocarb more significantly than D-amphetamine induces expression of the c-Fos protein in the nucleus accumbens core of C57BL mice. Injection of an 0.85% NaCl solution led to a moderate increase in the locomotor activity in the mice of both lines, while the c-Fos expression in the secondary motor cortex and septum was more pronounced in C57BL than in BALB/c mice.