The available wood supply in Uruguay comprises trees that grow so fast in intensively managed plantations that they reach saw timber size in 25 years or fewer. Trees harvested at this age contain high proportions of juvenile wood that may lead to lumber low in stiffness and strength. A project was conducted to characterize fast-growing wood, determine engineering properties, and assign visual structural grades of lumber. The present study evaluated properties of 15- and 25-year-old loblolly (Pinus taedaL.) and slash (Pinus elliottiiEng.) pine to better understand the current available locally produced wood material. A total of 175 stump bolts from trees from two commercial plantations provided inner and outer small clear specimens for property evaluation. Specific gravity, bending, compression parallel to grain and perpendicular to grain, and shear tests were conducted. Most properties significantly increased radially away from the pith. The outer wood appears to be denser, stiffer, and stronger than the inner wood in both plantations. Wood from 15-year-old San José trees showed significantly lower properties than 25-year-old Paysandú trees, and had considerably inferior properties compared with values listed in the Wood Handbook(US Department of Agriculture 1999). Our results on 25-year-old Paysandú small clear specimens showed properties similar to those of previous studies on small clear and structural size pieces. Therefore, it can be expected that lumber from 25-year-old Paysandú trees will eventually comply with required properties for structural use. A second on-going phase of this study addressing structural size specimens will help to establish more definite conclusions.