Summary This study includes malaria cases diagnosed by the Parasitology Unit of the Cayenne Hospital (French Guiana) using the same procedure from 1996 to 2003. We provide data for two main rural communities in slightly inland areas of eastern French Guiana (Cacao, Régina)
and for Cayenne, the capital of this French department. The frequency of bouts of malaria has been increasing rapidly since mid-2001, in these regions that were virtually considered to be malaria-free. This substantial increase of malaria appears mainly to involve Plasmodium vivax and
recent Brazilian immigrants. Other plausible explanations which could account for the observed trend are discussed.