The Sundarbans mangrove forest has a rich biodiversity of flowering plants and many of thesehave been used in traditional medicine although the flora remains comparatively uninvestigatedscientifically. Xylocarpus granatum, Xylocarpus moluccensis and Excoecaria agallocha methanolicextract showed a central nervous system depressant activity on the hole cross and open field testat 800 mg/kg dose level. The most significant depressant activity was observed in Xylocarpusgranatum followed by Xylocarpus moluccensis and Excoecaria agallocha. There was no depressantactivity observed in the models for Sarcolobus globosus. Further studies are required to confirm theactivity and to explain the mechanism.