the aim of the present study was to compare the direct detection methods of ehrlichia canis (blood smears and nested pcr), serological tests (dot-elisa and immunofluorescent antibody test - ifat), and demonstrate the most suitable test for the diagnosis of different stages of infection. blood samples and clinical data were collected from 30 dogs examined at the veterinary teaching hospital, unesp, jaboticabal, sp, brazil. the clinical signs most frequently observed were apathy, anorexia, pale mucous membrane, fever, lymphadenopathy, splenomegaly, hemorrhages and uveitis. evaluating the humoral immune response, 63.3% of the sera were ifat positive, while 70% were dot-elisa positive. by nestedpcr 53.3% of the samples were positive. comparing these techniques it was concluded that serology and npcr are the most suitable tests to confirm the diagnosis of canine ehrlichiosis, however it should be always treated as a complementary data to clinical and hematological evaluation. serology has an important role in the subclinical and in the chronic phase, npcr is recommended in the acute stage, and, especially, to identify the ehrlichia specie.