Wax-sizing improved the linear expansion (LE) of the particleboards under both pMDI resin contents used in this research and all LE values were controlled under the critical value of 0.35 % . The use of wax significantly reduced 24-h water absorption and thickness swelling compared to the control panels without wax. Wax-sizing at the moderate levels also showed positive influence on long-term water absorption and thickness swelling properties. Wax content levels, however, did not significantly influence water absorption and thickness swelling behavior. Wax-sizing had no evident negative effects on the bending properties of MDI-bonded bagasse particleboards under both resin contents, while it caused slightly negative effect on internal bond strength. Mechanical properties of all boards far exceeded the minimum values specified in ANSI A208.1 standard. The entire properties of the 5 % pMDI BPBs were better than those of the 3 % pMDI panels as expected.