A cross-sectional study was undertaken to determine the seroprevalence of Ehrlichia canis and Brucella canis in dogs in Morogoro Tanzania. The study was conducted between June and September 2010. A total of 100 randomly selected dogs were tested for the presence of Ehrlichia canis and Brucella canis antibodies using the Immunocomb ® dot-ELISA tests (Biogal, Israel). Epidemiological factors such as age, sex, breed, health status, body condition and tick infestation were studied. E. canis antibodies were detected in 25% (n=100) of the dogs. B. canis antibodies were not detected in any of the study dogs. The difference in seroprevalence between old and adult dogs was statistically significant (P<0.05). There was also a significant difference in seroprevalence between dogs in good and those in fair body conditions (P<0.05). Seropositivity to E. canis was not associated with the other epidemiological factors. This study provides the first serological evidence of E. canis infection but found no evidence of antibodies to B. canis in dogs in Morogoro. Canine ehrlichiosis was found to be a prevalent disease in Morogoro and calls for regular testing and treatment of clinical cases and tick control measures to protect dogs from E. canis infection. The study also points out the need for further investigation on the presence of canine brucellosis.