The ethanolic extract of Leucas aspera root was studied for its effect on the central nervous system(CNS) using pentobarbitone induced sleeping time test, the open field test and the hole cross testin Swiss albino mice. The present investigation revealed that the extract at the doses of 250 and500 mg/kg, significantly prolonged the pentobarbitone induced sleeping time in mice though theonset of sleep was delayed as compared to control. In open field test the depressing effect wasprominent from the second observation period (30 min) and persisted throughout the entireexperimental period (240 min). In the hole cross test, the depressing effect was observedsignificant from the third observation period (60 min) and persisted up to the seventh observationperiod (240 min) except at fourth observation (90 min) for 250 mg dose group and depressingeffect was significant from second observation (30 min) up to seventh observation period (240min) for 500 mg dose group. These results support the finding that Leucas aspera root may containbiologically active constituent(s) having CNS activity.