CÉLIO KERSUL DO SACRAMENTO 6 RESUMO -O declínio do mangostanzeiro (Garcinia mangostana L.) no litoral sul do Estado da Bahia é hoje o principal problema da cultura, sendo caracterizado por sintomas de murcha, amarelecimento, seca e queda de folhas. Este trabalho teve como objetivo acompanhar a evolução da sintomatologia da doença, isolar e identificar os potenciais patógenos causadores do declínio do mangostanzeiro. A doença começa com a necrose das radículas, a qual atinge as raízes secundárias, primárias e progride até à base do tronco que desenvolve lesões necróticas extensas. Os sintomas secundários são clorose, murcha e queda das folhas. ETIOLOGY OF THE DECLINE OF MANGOSTEEN IN THE SOUTHERN BAHIAABSTRACT -The decline of mangosteen (Garcinia mangostana L.) in the southern coast of the state of Bahia is today the main problem of the culture, being characterized by symptoms of wilting, yellowing, blight and defoliation. This study was aimed to follow the evolution of the symptoms of the disease, isolate and identify the possible pathogen of mangosteen decline. The disease begins in the roots and progresses toward the canopy, leading to plant death. Samples of infected tissue from diseased plants were taken to laboratory where the following fungal species were isolated and identified: Lasiodiplodia theobromae, L. parva, Mycoleptodiscus sp., Rhizopus sp., Stilbella sp., Aspergillus sp. and Trichoderma spp. Only Lasiodiplodia theobromae and L. parva were pathogenic to fragments of roots and stems in vitro and mangosteen seedlings in glass house, being the first species the more virulent. The taxonomy of the genus Lasiodiplodia and some conditions that influence the development of the disease in the field were analyzed.