Background: The aim is to study the central nervous system (CNS) depressant, anxiolytic, and antiepileptic activities of methanolic extract of Clerodendrum viscosum (MECV) leaves. Materials and Methods: The study comprised five groups each with 6 Wistar albino rats. The Group 1 or the positive control (phenytoin 30 mg/kg for the epilepsy model, and diazepam 1 mg/kg for the other models), Group 2 or negative control (0.9% NaCl at 10 ml/kg), and Groups 3–5 or the test drug group (MECV at 200, 400, and 800 mg/kg). Actophotometer test, staircase test, maximal electroshock seizure (MES) test, and the thiopentone sodium-induced sleep test, were used to study the various parameters. Results: The actophotometer test, MES, and staircase test (steps climbed) were analyzed using parametric tests. The sleep induction and staircase test (number of rears) were evaluated using nonparametric tests. A dose-dependent significant (P < 0.05) response was observed in the actophotometer test, sleep induction, and MES tests in comparison to control. In the staircase test at 200 and 400 mg/kg, increase in the number of steps climbed, and at 800 mg/kg decrease in both the number of steps climbed and rears were observed in comparison to control. Conclusion: MECV showed a dose-dependent CNS depressant action in the sleep induction and antiepileptic tests. A CNS stimulant action was observed at low dose (200 mg/kg) and depressant action at a higher dose (800 mg/kg) in the staircase test in comparison to control.