Detailed radial measurements of wood properties, taken at breast height, were obtained from control pollinated seedlings and a selection of 13 year old radiata pine ( Pinus radiata D. Don) clones. Using these data the key objectives of this study were to determine (i) the magnitude of mean clonal variation in modulus of elasticity (MOE) and properties affecting MOE (density and microfibril angle (MFA)) and (ii) whether there is a significant age × clone interaction for these traits. All wood properties were significantly affected by the main and interactive effects of age and clone. There was a relatively linear increase in both MOE and density with tree age, while MFA declined linearly with tree age. Values of density and MOE diverged between the clonal extremes from age 3 to age 12. After diverging markedly up to age 6, differences in MFA between clonal extremes remained relatively constant to age 12. At age 12, values for density, MFA, and MOE varied between clonal extremes by, respectively, 194 kg·m–3 (465–659 kg·m–3), 11.3° (9.6–20.9°), and 11.2 GPa (10.4–21.6 GPa). The seedling material had a relatively intermediate ranking, across the age range, for all traits considered.