The anxiolytic effect of carbamazepine was measured in rats placed in an elevated plus-maze. Doses from 5 to 40 mg/kg, ip, of carbamazepine increased the percentage of open arm entries as well as the percentage of time spent in the two open arms of the maze. Both of these measures are interpreted as indexes of anxiety. The total number of entries in either the open or the two enclosed arms, considered as an index of general activity, was not changed by the drug. Therefore, carbamazepine caused a selective anxiolytic effect as measured in the elevated plus-maze, which is predictive of clinical efficacy.