Wild cacao trees (Theobroma cacao L.) found in south-eastern French Guiana form a particular genetic group, the “Guiana” group, which could be used in cacao breeding. Since 1987, CIRAD has set itself the objective of collecting and characterizing those cacao trees, carrying out agronomic and sensory assessments, and studying their diversity. The main results acquired are presented. Four surveys took place from 1987 to 2012 in the upper reaches of the Oyapok and Tanpok rivers. The plant material collected, from 225 mother-trees, has been planted in a collection at CIRAD's Sinnamary station, as open-pollinated progenies or clones. The trees are observed individually for ten years for various agronomic descriptors: juvenile growth, adult vigour, early yielding, yields, “cropping efficiency”, percentage of rotten pods and average pod weight. Various morphological, biochemical and molecular descriptors have been used to study the diversity of the “Guiana” group. Resistance to black pod rot caused by stramenopiles of the genus Phytophthora (P. palmivora and P. capsici) is assessed in early tests and many resistant clones have been identified. Sensory studies have revealed a cocoa flavour that is statistically better than that of the industrial reference. This germplasm is exceptional. It is therefore important to continue surveys in French Guiana (some zones have yet to be surveyed) and maybe in the Guiana Shield, and to assess all clones for their performance in relation to other pests and diseases. (Texte intégral)