We have previously reported DNA polymerase activity of Entamoeba histolytica. The present study was aimed to compare the activity of E. histolytica with that of E. dispar, which formerly was known as the non-pathogenic strain of E. histolytica. The level of activity of E. dispar was comparable to that of E. histolytica. Also, dependence of the activities of both species on pH, salt, Mg 2 + , and sensitivity to inhibitors of mammalian DNA polymerases were almost the same. Thus the E. dispar enzyme was very similar to the E. histolytica enzyme quantitatively and qualitatively.