The high incidence of diarrhea in the population demands a search for new therapeutic options and easy access, mainly from plant-based sources. Leaves and bark of Guazuma ulmifolia Lam. (Sterculiaceae) are popularly employed against diarrhea. However, no information was found in the literature about this supposed property of the drug. In this study we evaluated in vivo antidiarrheal activity of stem bark extracts from G. ulmifolia in mice, and in vitro antimicrobial activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Salmonella sp., Shigella flexneri, and Pseudomonas aeruginosa by using the microdilution method. The n-BuOH semipurified fraction (GU#3) significantly reduced intestinal motility. The extracts did not show antimicrobial activity. G. ulmifolia Lam. had non-specific antidiarrheal, and antimotility activity in the experimental models studied, and could be used as an alternative treatment for non-infectious diarrhea.