The study aims to determine the existing condition of mangrove as well as to asses dependency of coastal communities to the mangrove system at districts Biduk-biduk, East Kalimantan. The  primary data related to the mangrove condition was conducted using random sampling while sosio-ecology was taken through direct interviewing. The results obtained composition studies  as many as 31 species of mangrove species consisting of 13 species of true mangrove and 18 species of mangrove associates, where the average value of the density of mangroves in the study site was 1489 individuals/ha. True mangrove species found in this study include Acathus ilicifolius, Aegiceras corniculatum, Brugueira gymnorhizza, B. parviflora, Ceriops tagal,Excoecaria agallocha, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata, Scyphiphora hydrophyllacea, Sonneratia alba, Sonneratia lanceolata, Xylocarpus granatum. Social studies results obtained information that the level of utilization direct of mangrove forests by the communities in the districts Biduk-biduk was relatively low as they were aware with the mangrove functionnement ecologically.