Background: Ehrlichiosis is a non contagious infectious disease, mainly transmitted by thick bites. In 1998, this infection was detected in dogs, for the first time, in Chile. Aim: To establish if there is human exposure to Ehrlichia sp in Chile. Material and methods: Blood samples from 17 dogs with ehrlichiosis and 19 humans who had contact with them were studied to determine human exposure to Ehrlichia equi and Ehrlichia chaffeensis in Chile. Samples were analyzed by indirect inmunofluorecence and by polymerase chain reaction (PCR). Results: Six dogs had positive titers against both species of ehrlichia; 2 with titers of 1/256; 3 with titers over 1/512 to Ehrlichia equi and titers of 1/256, 1/128 and 1/64 to Ehrlichia chaffeensis respectively, and 1 with titers of 1/256 to Ehrlichia equi and titers of 1/128 to Ehrlichia chaffeensis. Two of the 19 humans, had positive titers against both antigens (1/128). PCR reactions were negative in both human and canine sera. Conclusions: These results confirm that human exposure to Ehrlichia sp. Epidemiological surveillance for human ehrlichiosis should be implemented in the country (Rev Méd Chile 2003; 131: 67-70)