Giardia, Entamoeba, Isospora and Cryptosporidium are important protozoan parastites that caused diarrhea in human and animals. In the present study, fecal samples were collected fresh, directly from the rectum of 112 stray dogs in Ilam province. Giardia and Entamoeba were concentrated by using the formalin ether sedimentation method followed by the trichrome and iodine staining technique andCryptosporidium  oocysts  were  concentrated  by  using  the  formalin  ether  sedimentation  method  followed by the modified Ziehl-Neelsen staining technique. Of 112 stray dogs, protozoan infections were detected from feces of 46 dogs (41.07%) that Giardia infection was detected from feces of 21 dogs (18.75%), Isospora 17 (15.17%), Cryptosporidium 8 (7.14%) and synchronization infection to 2 protozoan in 9 dogs (8.03%) and to 3 protozoan in 3 (2.67%). In the present study not observed to Entamoeba. No statistically significant differences in prevalence of protozoan parasites occurred between female (34.21 %) and male (55.5 %) stray dogs (p>0/05). But statistically significant differences in prevalence occurred between 1≥0 and 0 ≥1 stray dogs (p>0/05). So that stray dogs of Ilam province can cause infection of human water and food sources.