Resumo. ABSTRACT The objective of this study was to adjust and select probability density functions that describe the diametric distribution of Poincianella bracteosa Tul, Mimosa ophthalmocentra Mart. ex Benth e Manihot carthaginensis subsp. glaziovii (Muell. Arg.) Allem species, and for this species as whole, which occured in Caatinga biome, in the municipality of Floresta, in the semiarid region of Pernambuco state. The study was conducted in an area with disturbance history with approximately 10 ha, where it was installed 20 plots (20 x 20m), in a symmetric way, where all the trees with circumference at the breast right (CBH) ≥ 6cm were identified and their diameters and heights were measured. It was tested the probabilistic functions such as: Weibull 3 parameters, Jonson’s Sb, Normal, Log-nomal, Gamma, Beta and Meyer. A class interval of 2 cm was used and Kolmogorov-Smirnov test was used as the selection criterium. It was found that the Weibull 3 parameters was the best function described the diametric distribution for Mimosa ophthalmocentra e Manihot carthaginensis . For Poincianella bracteosa Johnson’s Sb was the ideal one. The existence of strong disturbance observed in the study area, is explained by a unimodal distribution, reflected in the three species, so that the area deserves due attention so that this process ceases.