About 3,000 European and Zebu cattle sera from various rearing areas of French Guiana were examined by enzyme-linked immunosorbent assay (ELISA) for detection of specific circulating antigens of Trypanosoma vivax and for detection of antibodies to Trypanosoma species with reagents provided by ILRAD. For the whole country, the seroprevalence rate is 29%. Infection was detected everywhere in French Guiana, but seroprevalence rates were different from place to place, depending on the epidemiological situation, the abundance of vectors (stable-flies and horse-flies) and the management. We could generally classify herds in three epidemiological situations: high, low or intermediate seroprevalence. Despite the absence of clinical signs during two/three years, notably during this epidemiological survey, the antigen and/or antibody seroprevalences of T. vivax show a stable infection in the country. Natural pathogenicity of Guianan T. vivax should be confirmed; a very low parasitaemia or an extra-vascular foci might explain the apparent absence of bloodstream forms between two outbreaks. The epidemiological control will be maintained to determine whether outbreaks are due to an immunological failure to the present serodemes, to the spreading of new serodemes, or to other epidemiological parameters.