The graft copolymerization of methyl methacrylate (MMA) onto non-mulberry silk fibre Antheraea assama using potassium permanganate (KMnO4)-oxalic acid redox system was carried out. Effects on grafting of various parameters, concentration of monomer and initiator, reaction time and temperature were studied. The graft yields increased significantly with increase of the monomer concentration and with increasing concentration of initiator, Mn(IV), up to 6 x 10(-3) M, but decreased thereafter. The rate of grafting increased progressively with the increase of reaction time up to 4 h and then decreased. The extent was also dependent upon reaction temperature, and at 50 degrees C, the graft yield was maximum. The characteristics of the grafted products were evaluated by infrared spectroscopy, while the thermal decompositions of the grafted fibres were studied using thermogravimetric (TGA) and differential thermogravimetric (DTG) techniques at heating rates 20 degrees C and 30 degrees C min(-1) in static air in the temperature range 30-800 degrees C. The grafted fibres were thermally more stable and more hydrophobic in nature than the ungrafted fibres.