A seroepidemiological survey was made of the prevalence of antibodies reactive, with Ehrlichia canis in stray and pet dogs from five geographical regions of Israel. Serum samples from 410 dogs were assayed by an indirect fluorescent antibody test and serum reactive at a 1:20 dilution or greater was considered positive. The overall seroprevalence was 30 per cent with 23.9 per cent in pet dogs and 37.5 per cent in stray dogs. The seroprevalence in apparently healthy pets (17.6 per cent) was lower but did not differ significantly from the seroprevalence in sick animals (26.6 per cent). The seroprevalence was highest in the north of Israel and lowest in the central hilly area, and followed the same trend in both the populations sampled. Young dogs (under one year old) had a lower seroprevalence (14.9 per cent) than adult (one to eight years) (36.4 per cent) or older dogs (over eight years) (34.2 per cent). The results demonstrate that dogs in Israel are extensively exposed to E cants and indicate that ehrlichiosis is endemic in this area of the Middle East.