We developed and standardized an indirect immunofluorescence test for detection of IgG and IgTotal for diagnosing human Ehrlichiosis. It was used as antigen to DH82 infected cells with Ehrlichia chaffeensis Sapulpa strain; it was considered a dilution of 1/64 as positive. We evaluated sera from 130 febrile patients negative for Rickettsiosis and Carrion disease from Ancash, who entered at Instituto Nacional de Salud (Lima, Peru) between 2004 and 2006. We found that 12 (9.2%) sera were positive for Ehrlichiosis. Given that Ehrlichiosis is an emerging disease and with the development of this test, it should start monitoring and epidemiological studies of Ehrlichiosis in Peru.