Fragments of floodplain forests occur naturally in the Araguaia plain between the states of Tocantins and Mato Grosso on the ares of Cerrado. These fragments happen in form of natural depressions, which are located in areas of floodplains in the State of Tocantins, which favors its flooding and, consequently, the largest period of water retention during periods of high precipitation. The objective of this study was to characterize the structure of a fragment of floodplain forest of approximately one hectare, inserted in area of Campo Sujo, in Lagoa da Confusão, TO. Were sampled all the tree/shrub individuals with circumference at 1,30m of the soil (CAB) ≥ 15 cm. On the whole, 665 individuals, 34 families and 49 species were found. The species with larger cover value, in descending order, were Sclerolobium paniculatum var. rubiginosum (Mart. former Tul.) Benth., Calophyllum brasiliense Cambess. and Licania apetala (E. Mey.) Fritsch.. The richest families were Fabaceae (8), Arecaceae, Chrysobalanaceae and Vochysiaceae (3). The Shannon diversity index (H') was 2,97 nats/ind. The distribution of diameter classes showed an inverted "J" curve.