Objective: Canine Ehrlichiosis is a tropical tick-borne disease caused by Ehrlichia canis. It produces a subclinical infection and causes fever and some hematological abnormalities.

Design: Blood samples from 1800 domestic and wild dogs were obtained and serological tests were used to detect Ehrlichia spp.

Materials and Methods: Blood samples from 980 dogs (510 domestic dogs and 475 wild dogs) in West Azarbaijan and 820 dogs (520 domestic dogs and 300 wild dogs) in East Azarbaijan were obtained. Hematological and biochemical tests and also indirect immunofluorescence assay (Ristic et al, 1986) were used for diagnosis of disease and the variants of the organism.

Results: The results shows that 67% of wild dogs and 38% of domestic dogs in West Azarbaijan were serologically positive for Ehrlichia. These values for east Azarbaijan were 58% and 39% respectively.

Conclusion: Ehrlichiosis in Iran and especially in Azarbaijan is one of the most prevalent tick borne diseases. Despite of current imagination, according to results of our study, canine Ehrlichiosis especially in wild dogs in Iran has a high prevalence and can cause an acute to chronic hemolytic anemia. and it is necessary to pay more attention to this fact by field's veterinarians. The main variants diagnosed were E.canis (75%), E. platys (20%) and E. equi (5%). In some cases, mixed infection and synchronized Leishmaniasis also were seen.