Research on secondary succession in the Amazon basin has attracted great interest in recent years. However, methods used to classify successional stages are limited. This research explores a method that can be used to differentiate regrowth stages. The vegetation inventory data were collected in Altamira, Bragantina, Pedras, and Tome-Acu of the eastern Amazon basin. A nested sampling strategy, organized by region, site, plot, and subplot, was employed for field data collection. Above-ground biomass (AGB). forest stand volume (FSV), basal area, average stand height, average stand diameter (ASD), age, ratio of tree biomass to total biomass (RTB), ratio of tree volume to total volume, and ratio of tree basal area to total basal area were calculated at the site level. Canonical discriminant analysis (CDA) was used to differentiate successional stages and to identify the best forest stand parameters to distinguish these stages. This research indicates that the CDA approach can be used to classify successional forest stages, but using RTB or a combination of two stand parameters such as AGB and ASD are more feasible and recommended in practice. (C) 2003 Elsevier Science B.V. All rights reserved.