Background: Entamoeba histolytica is a pathogenic protozoan parasite, causing different symptoms such as dysentery and amebic abscess, which is morphologically indistinguishable from nonpathogenic E . dispar. This study was performed for differential diagnosis of two E. by PCR method.

Matrials & Methods: A total of 450 stool samples were collected from the patients reffering to the clinical laboratory of Taleghani Hospital. The samples were examined by direct and formaline detergente methods. Five cases of E. histolytica or E. dispar were reported and stool samples were sent to the Department of Parasitology & Mycology, Shaheed Beheshti University of Medical Sciences and Health services. After cultivating in Robinson’s medium and indentifying, DNA was isolated and E. histolytica or E. dispar were recognized by PCR with two sets of species-primers of locus 1-2 gene.

Results: E. histolytica or E. dispar infection was reported 1.1% by direct and formaline detergent methods. PCR with those primers amplified about 430 bp fragment in four samples was identified as E. dispar. 4 isolates E. dispar were reported by PCR method. One of samples was not cultivated in Robinson’s medium and eliminated from the study.

Conclusion: Identification of E. histolytica or E. dispar is important in clinical and an epidemiological study and PCR method is useful for differential diagnosis of two E. Species.