Background: Grewia carpinifolia is a plant commonly used in the tropics to manage various central nervous system (CNS) disorders. However, despite its widespread use no scientific work has been reported to validate these claims.

Objectives: To evaluate the activity of G. carpinifolia as it affects behaviour using animal model.

Methods: Twenty five adult Wistar rats were randomly divided into five groups (A-E). Group A served as control (given only distilled water), Groups B,C, D and E were administered with single oral dose of ethanol extract of G. carpinifolia leaf at 100, 200, 400 and 800 mg/kg body weight respectively for twenty eight days consecutively. Subsequently, open field test, negative geotaxis and hanging wire test were performed. Body and brain weights were measured and histological examination of the brain was also performed.

Results: At the tested doses, the extract significantly increased the time spent on the hanging wire and decreased locomotor activity at 800 mg/kg. No significant difference was observed in body and brain weights of extract treated groups when compared with the control. No visible histological lesion was also observed.

Conclusion: The plant extract may improve muscular strength at tested doses and possess CNS depressant activity at 800 mg/kg.