Degradation studies of poliphenols of leaves and branchs of Inga sp., Mabea caudata Pax ex K. Hoffn., Mezilaurus itauba (Meissn.) Taub ex Mez., Vatairea sericea Ducke and Protium sp. were carried out during 155 days in two experimentals lakes in the states of Amazonas. In the 1st lake the vegetation remained intact and in the 2nd the vegetation was deforested. Phenolic compound determinations were based on the Follin-Denis method. The object of the present study was to know the degradation rate of phaneroghame vegetation in aquatic environment. Inga sp. and Mezilaurus itauba showed greater decomposition In the 1st lake than in the while Mabea caudata. and Mexilauris itauba showed high decomposition in the second lake.