© Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, 300001 Nigeria. All rights reserved. Methods: The antidiarrhea activity of honokiol was investigated using castor oil-induced diarrhea as well as neostigmine-induced increase in small intestine transit in mice. In castor oil-induced diarrhoea test, mice received honokiol (25, 50 and 100 mg/kg BW) orally once daily for 1 day and the mice’ droppings were observed. In small intestine transit test, mice received honokiol (25, 50 and 100 mg/kg BW) orally once daily for 4 days and the percentage distance travelled by charcoal meal was noted to determine. For the determination of anti-oxidant activity, with 50 mg/kg vitamin E as positive control, the mice were administered with 25, 50 or 100 mg/kg honokiol orally and daily for 14 days. The activity and gene expression of antioxidative enzymes as well as antioxidant status were monitored to assess the antioxidant potential of honokiol. Purpose: To evaluate the antidiarrhea and antioxidant properties of honokiol extracted from Magnoliae officinalis cortex (bark of Magnolia officinalis), an important medical material in traditional Chinese medicine, for treating diseases such as diarrhea and thrombotic stroke. Results: All doses of honokiol showed (p <0.001) significant inhibitory activity against castor oil- induced diarrhea when compared with model control (diarrhea Index, 1.10 vs. 1.39)-. Honokiol at all doses also reduced neostigmine-stimulated small intestinal transit by approximately 16% in comparison with -neostigmine control group-(59.0% vs. 70.1%). Compared with control (no honokiol), the activities of catalase (CAT), glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) in the plasma (CAT, 7.31 vs. 13.21 U/mL; GSH-Px, 439.6 vs. 608.9 U/m; T-SOD, 82.2 vs. 109.8 U/mL) and liver (CAT, 7.73 vs. 14.39 U/mg; GSH-Px, 167.6 vs. 202.7 U/mg; T-SOD, 44.3 vs. 53.9 U/mg) were significantly enhanced by honokiol (p <0.01). CAT and GSH-Px gene expressions were also significantly enhanced by honokiol (p <0.05), compared with control (no honokiol) (CAT, 0.32 vs. 0.39; GSH-Px, 4.49 vs. 5.80). Additionally, total antioxidant capacity was increased by 60% with 100 mg/kg honokiol. Conclusion: The results provide some justification for the use of Magnoliae officinalis cortex as an antidiarrheal remedy in Chinese traditional medicine. The fact that honokiol also enhanced both the non-enzymatic and enzymatic antioxidant defense systems, suggests its potential as a natural antioxidant.