Zinc plays an important role in immunity and diarrhea. Zinc deficiency is common in acute and chronic diarrhea and leads to impaired immune function. Studies show that zinc supplementation in children with diarrhea reduces duration and severity of diarrhea episodes. It does so by accelerating regeneration of the intestinal mucosa and enhancing cellular immunity. As zinc deficiency is prevalent in developing countries, zinc supplements can be useful as both a preventive and therapeutic intervention for diarrhea.