Gastroenteritis is one of the most common reasons for physician visits worldwide. Annually, 2 or 3 billion people are estimated to suffer from gastroenteritis. Children under 5 years old are reported to experience gastroenteritis 3.2 times a year. Gastrointestinal infections are more prominent in geographic regions with poor sanitation and health systems. Acute gastroenteritis is generally defined as a decrease in the consistency of stools (loose or liquid) and/or an increase in the frequency of evacuations (typically ?3 in 24 h). Diarrhea typically lasts less than 7 days and not longer than 14 days. Viruses, bacteria, protozoa, helminths, and fungus cause gastrointestinal system infections. Antibiotic treatment is indicated only for bacterial enteric infections and indications. The most important step for treatment of gastroenteritis is rehydration and replacement therapy for restoring fluid and electrolyte balance. In most of the cases, oral rehydration therapy is adequate for the treatment. © 2014 by Pediatric Infectious Diseases.