The objective is to evaluate the primary mechanical and physical properties of particleboard made from hammer-milled rice straw particles of six different categories and two types of resins. The results show the performance of straw particleboards is highly dependent upon the straw particle size controlled by the opening size of the perforated plate inside the hammer-mill. The static bending and internal bonding strength of polymeric diphenylmethane diisocyanate (pMDI) resin-bonded boards initially increase then decrease with decreased particle size. The thickness swelling, water absorption, and linear expansion of particleboards decrease with increasing particle size. Compared with pMDI resin-bonded panels, the rice straw particleboard bonded using urea-formaldehyde resin exhibits much poorer performance. The optimized panel properties, obtained when using 4% pMDI and straw particles hammer milled with a 3.18 mm opening perforated plate, exceeded the M-2 specification of American National Standard for Wood Particleboard. Published by Elsevier Ltd.