Giardia lamblia is a flagellated protozoan that infects the duodenum and small intestine. It is one of the most common intestinal parasites throughout the world. Transmission occurrs via contaminated water or food. It is also spread by person to person contact. The clinical features of infection might varied from asymptomatic to symptoms of diarrhea, epigastric pain, nausea, vomiting and weight loss. The prevalence of Giardia infection in Iran were reported to be about 14% in children and 6% in adults, therefore it should be considered as an important health problem and early detection of infection, appropriate treatment and improvement of health could dramatically reduce the rate of infection. The enzyme immunoassays detecting protozoan soluble antigens in stool and ELISA are widely used. in addition to higher sensitivity and specificity, a large number of faecal specimens can be screened at one time by these methods with less technical skills, less costs, less labour, and less laboratory turnaround times. All samples were also examined by ELISA test and agreement between results of ELISA and direct stool smear were measured.