A paludometric study of the 1970-1979 decade in French Guyana, shows a 2.7% plasmodic index, with a mean incidence of 6.4 per 1,000 habitants and a very high prevalence of P. falciparum (84%). Anopheles darlingi, the principal vector, still remains sensitive to DDT after 30 years of insecticide utilisation. The autochthonous malaria occurs permanently in the bordering areas between Guyana and Brasil at the East and between Guyana and Surinam at the West. In the other parts of the country, in the Island of Cayenne particularly, seasonal epidemics appear during the dry months and are due to imported Plasmodium. Sanitary reglementation of immigration and an actualisation of the anti-vectorial programme control are proposed as prophylactic measures.