Resumo. The present study had as its main objective to characterize the diameter distribution of an experimental plantation of ‘candeia’ trees submitted to different treatments (age, spacing and silvicultural treatments), by adjusting several probability density functions. Subsequently, a prognosis of the selected function parameters in relation to age was conducted. The probability density functions tested were: Gamma, Normal, Log-normal,2-parameter Weibull (2P) and 3-parameter Weibull (3P) for the different study groups. The selection of the best fit was based on the Kolmogorov-Smirnov test with a probability of 95%. The Weibull 3P function present the best fits for the majority of the treatments, especially for pruned trees, being thus chosen for the prognosis of the parameters according to age. It was detected that pruning affected the scale parameters, but not the shape parameters, while spacing did not influence the function parameters in a significant manner. Hence, linear equations were adjusted for the prognosis of the parameters in relation to age. A simulation was conducted considering pruned and not pruned trees in order to evaluate the behavior of the diametric distribution in relation to the plantation age, in which it was found that the parameterized equations satisfactorily distinguished between the pruned and not pruned ‘candeia’ plantations.