Background: Clerodendrum viscosum is one of the most well-known plants in traditional practices. The study aims to explore the antidiabetic, antidiarrheal and sedative effects of methanolic extract of Clerodendrum viscosum roots (MECV) in mice. Methods: For each experiment, four groups of animals were used consisting of three mice per group. Each group was treated individually: group I treated as negative control, Group II received reference drug of each experiment, Group III and IV received MECV at 200 and 400 mg/kg body weight, respectively. Antidiabetic effect of MECV was evaluated by oral glucose tolerance test. Antidiarrheal activity was examined by the method of castor oil induced diarrhea and reduction in amount of diarrheal feces was determined. To assess the sedative activity of MECV, total sleeping time was determined in phenobarbitone induced mice. Results: MECV showed statistically significant (p<0.05) blood glucose lowering activity which was comparable to the standard drug, glibenclamide and the effect was found to be dose dependent. The extract reduced the diarrheal feces in mice by 51.85% and 65.56% at 200 and 400 mg/kg doses, respectively. The observed activity was found significant (p<0.05) in comparison to the positive control. Also, the test extract showed significant (p<0.05) sedative activity with respect to the control suggesting that the extract potentiated the phenobarbitone induced sleeping time. Conclusion: This is the first report on the therapeutic importance of methanolic extract of Clerodendrum viscosum roots in diabetes, diarrhea and sedation and thus supporting the uses of the plant in traditional medicine.