Blends of natural rubber and low-density polyethylene were prepared in different weight compositions in presence of dicumyl peroxide and maleic acid anhydride. The effects of rice husk (RH) content and a silane coupling agent, that is, 3-aminopropyl triethoxy silane (3-APE, 1 wt% of filler content) on the physicomechanical properties and mass swell of the tested blend were investigated. The incorporation of untreated RH into the blend improved Young's modulus, hardness but decreased tensile strength, elongation at break, impact strength, and mass swell. Incorporation of 3-APE has produced composite with improved tensile strength, Young's modulus, hardness and impact strength with a sharp decrease in elongation, and better mass swell in comparison with untreated one. The effect of gamma-irradiation doses on retained physicomechanical properties of RH (30 phr) filled blend samples before and after silane treatment was investigated at ambient temperature. The efficiency of silanized RH (30 phr) was also evaluated by the studies of the surface morphology (scanning electron microscopy) and thermal properties (thermal gravimetric analysis and thermal mechanical analysis).