Abstract: OBJECTIVE To investigate the effect of the all-trans-retinoic acid(ATRA) on the nervous system of mice by employment mice spontaneous activity test, coordination test, and the synergistic effect of the threshold dose of sodium pentobarbital test. METHODS ICR mice, half male and half female, were randomly assigned as vehicle, 250.0, 50.0 and 10.0 mg·kg^-1 ATRA groups according to body weight. After 12 h of fasting (with water), the mice in each group were given the corresponding dose of ATRA respectively by intragastrical administration, dosing volume was 0.02 mL·g^-1. As to mice spontaneous activity test, the mice spontaneous activity was determined before and after administration of ATRA for 60, 120, and 180 min. Mice coordinated test was carried out by determining the residence time of mice on the rotary rod 120 min after administration. The synergistic effect of the threshold dose of sodium pentobarbital and ATRA was analyzed 120 min after administration of sodium pentobarbital. The numbers of sleeping mice were calculated. RESULTS The 250.0 mg·kg^-1 ATRA could significantly reduce the number of spontaneous activity of mice, 50.0 or 10.0 mg·kg^-1 ATRA was found to reduce the trend of spontaneous activities in 120, 180 min; 250.0, 50.0, or 10.0 mg·kg^-1 ATRA had no significant effect on the coordination of mice. ATRA had no synergistic effect with the threshold dose of sodium pentobarbital. CONCLUSION ATRA can reduce the number of spontaneous activity of mice, and has no significant effect on the coordination of mice, and has no synergistic effect with the threshold dose of sodium pentobarbital.