Resumo. The commercial forests plantation contributes decisively to generate socio-economic and environmental benefits, providing sustainability at the forest-based industries. The Eucalyptus grandis Hill ex Maiden stand out as one of the most cultivated species for reforestation in Brazil. The objective of this study was to determine the relationship between precipitation and wood production for 23-year old Eucalyptus grandis from a commercial plantation in Rio Claro, Rio de Janeiro state, Brazil. The annual increment of wood was determined by the X-ray densitometry, which provides a detailed wood density profile in radial direction for each sample. One year of the tree life was considered because this the period for the formation of two consecutive latewood rings formation, which corresponds to two high density peaks. The results showed a positive correlation between precipitation data and annual increment of wood, revealing the dendroclimatology potential of this species in this region.