Resumo. This study, conducted in a 27-year-old Araucaria angustifolia stand in the municipality of Quedas do Iguaçu (PR) county, aimed to estimate tree components, understory and accumulated litter biomasses. Biomass was estimated through regression equation adjustments, with 21 trees felled, distributed among 7 diametric classes, and with litter and understory based on known sample unit areas. Total stand biomass was 241.92 Mg ha-1, with 82.2% composed of Araucaria angustifolia, 9.6% composed of understory and 8.2% composed by litter. Considering only Araucaria angustifolia, the biomass was of 198.62 Mg ha-1, composed of wood (51.5%), bark (14.7%), roots (13.0%), lives branches (11.8%), aciculated branches (6.6%) and dead branches (0.5%). Relative biomass production for the wood component may be low, when compared to other forest species, mainly due to the high allocation in the bark component.