Prolonged and repeated low-frequency stimulation (2 imp/s, 20-30 min, 3-4 times) of the striatum disorganized rat's circadian motility. Attenuation of amplitude rhythm and shift of its acrophase to early night hours were observed. Bilateral striatectomy increased the motor activity after light switching-off and rhythm splitting to ultradian components. It is suggested that the striatum as a secondary oscillatory messenger may participate in motor maintenance of circadian motility.