Abstract In the antidiarrheal activity evaluation, the aqueous leave extract of Ziziphus mauritiana was found to be effective against castor oil – induced diarrhea in Wistar strain albino rats at the doses of 200, 400 and 800 mg/kg body weight, the fecal droppings decreased and percentage inhibition was 51.05 %, 54.48 % and 58.10 % respectively which was dose – dependent and statiscally significant at (p < 0.05). The control group showed typical diarrheal signs with 0.00 % inhibition while the group given the standard antidiarrheal drug loperamide 5 mg/kg body weight was protected 100 %. In the intestinal transit of charcoal meal method, the percentage inhibition of the extract treated rats were 19.07 %, 06.00 % and 18.94%, the atropine sulphate (3 ml/kg) body weight treated group was inhibited by 41.96 % and the inhibition was not dose dependant. In the intestinal fluid accumulation method, the extract inhibited the intestinal fluid accumulation in rats by 28.04 %, 43.93 % and 54.21 % relative to the control group with 0.00% inhibition. The group given atropine sulphate had 85.05 % inhibition. The results of this study suggest that the aqueous leaves of Ziziphus mauritiana has antidiarrheal effect, this might have justified its traditional use in the treatment of diarrhea.