Abstract.Recent publications on the coral community of the Tuamotu archipelago have dealt with the Mururoa and Taiaro atolls, with virtually no information available on Takapoto. Consequently the reefs of this atoll were studied using SCUBA to a depth of 70 m and in different biotopes such as patch reefs of the lagoon, and external or protected slopes. A description of the various coral communities is given; specific diversity, ecological valence, community composition, percent coverage, and constructive potential is discussed in relation to abiotic factors.SummaryIn June 1978 the coral associations of the atoll Takapoto, Tuamotu Archipelago, were studied down to 70m by SCUBA (D.Kühlmann) and the corals later determined by J.‐P. Chevalier(†) in Paris. Fifty‐eightScleractiniaand five hydrocorals were observed in the reefs.The highest diversity of species exists in clear, moderate moving waters on a moderately inclined substratum. An ecological valence was established as euryoecious forMontipora verrucosa, Porites lobata, Favia speciosaandMille‐pora platyphylla.Deep water species areLeptoseris porosaandFungiacf.granulosa.The coral associations show characteristic differences at the windward and leeward outer slopes as well as at the patch reefs of the lagoon; these differences are regulated by distinctive hydrodynamics, sedimentation processes, and substrate types as the most effective environmental factors in smaller habitats. The highest degree of coverage of hard corals is found at the windward slope between 10 and 20 m with 90%, the lowest with less than 10% at the slopes of the patch reefs in the lagoon because of the strong sedimentation. The most important reef constructors in the different habitats are listed.RemerciementsJ'exprime ma gratitude à B. Salvat, qui m'a fourni la possibilityé de travailler à 'Antenne de Moorea du Muséum national d'Histoire naturelle, et sur 'atoll de Takapoto. Mes remerciements s'adressent également au Ministére des Universités de la République Démocratique Allemande pour la prise en charge du voyage Berlin‐Tahiti‐Berlin. A.Hauti, Chef du Sérvice de la Pêche, Station de Recherche Nacre et Perliculture de Takapoto, a mis á ma disposition tous les moyens nécessaires á la plongée sur les récifs, embarcations comprises. 'aide de Cigi, Puhipuhi, Bernard, Ismail et Pari fut toujours éfficace. Je n'oublierai pas 'amitie profonde de mes compagnons, G. Richardet G. Vergonzanne. Aprés le décès de J.‐P. Chevalieren 1981, M. Pichon, B. Thomassinet H. et J. ZIBROWIUS ont aimablement