Question: What are the relative roles of tree growth, mortality and recruitment in variations of aboveground biomass in tropical forests? Location: Paracou, French Guiana. Methods: We quantified the contribution of growth, recruitment and mortality to total biomass of stands (trees DBH _ 10 cm) in six 6.25-ha permanent plots over 16 yr. Live biomass stocks and fluxes were computed for four separate size classes. Results: All plots showed increasing biomass stocks over the study period, with an average value of 10.9Mgha_1 yr_1. Plots aggrading biomass were characterized by either minor biomass losses due to mortality or substantial increases in the biomass of large trees (DBH _ 60 cm). Conclusions: Within the study period, the rarity of mortality events could not counter-balance the slow permanent increase in biomass, resulting in an apparent increase in biomass. Accounting for such rare events results in no net change in biomass balance.