AbstractThis study examines the dimensional stability of fast-growing poplar clones wood after treatment by impregnation with methyl methacrylate (MMA). Six hybrid poplar clones from one plantation in Quebec were sampled. The effects of hardening with MMA on density as well as longitudinal, radial, tangential, and volumetric swelling properties (S), water uptake capacity (D), anti-swelling efficiency (ASE), and water repellent efficiency (WRE) after soaking were investigated. Hardening treatment increased the density of all poplar woods by 1.2 to 1.6 and decreased the inner water migration rate during soaking. S and D values of hardened woods were significantly lower than those of controls, depending on the clone type. ASE and WRE values suggested that incorporating MMA effectively improved the dimensional stability of poplar wood at the early soaking stage, but was less effective in the long term.