Diarrheal disease is the second leading cause of death in children under five years old in the world. In developing countries such as Iran, children under three years old experience on average three episode of diarrhea every year. Diarrhea is usually a symptom of an infection in the intestinal tract which can be caused by variety of bacterial, viral, and parasitic organism. Campylobacter one of the most common cause of human bacterial gastrointestinal disease, accounting for 5-7 % of caused gastrointestinitis. The large numbers of campylobacter infections were missed by laboratories, because there is no enough cultural facility for detection of campylobacter sp. In this issue you study a case report and in the following suggested that a simple direct gram stain of stool may be very useful to diagnosis Campylobacter infection.