Background & Objectives: Diarrhea is one the important causes of mortality among children in developing countries. The effect of zinc supplementation in reduction the rate of diarrhea is controversial. The aim of this study was to evaluate the effect of zinc supplementation on the severity and duration of diarrhea in children less than 5 years old hospitalized in Ali-Asghar hospital in Ardabil, 2005.

  Methods: This study was a double-blind, randomized, placebo-controlled trial including 228 children with acute diarrhea. The subjects randomly assigned into two placebo and experimental groups (114 patients in each group). The placebo group received glucose (5%), while the experimental group received 20 mg/day Zn sulfate. The severity and duration of diarrhea were assessed during the study. Data were analyzed using Chi-square, Pearson correlation coefficient tests and Students t-test by SPSS software.

  Results: Our findings showed that most of the patients in both groups were male (age range 1-12 months, weight range 3-11 kg, weight percentile 3-50). These children had breast feeding and complete vaccination. They were the first baby in their family and the majority of them were from urban area (Ardabil city). The severity of diarrhea in zinc supplemented children (74.6%) was less than placebo group (89.5 % ) (p=0.037). There was no significant difference between two groups in the duration of diarrhea (p=0.737). There also was no relationship between the severity of diarrhea and weight percentile (p= 0.085).

  Conclusion: Our data indicate that zinc supplementation reduces the severity of acute diarrhea and could be advised in children with acute diarrhea.