In order to study the potential of increasing the weather stability of natural rubber latex for use as a water-based contact adhesive, the natural rubber latex was modified by graft copolymerization with n-butyl acrylate (BA) and methyl methacrylate (MMA). The grafting reaction was carried out using emulsion polymerization at 60°C. Potassium persulfate was used to initiate polymerization. Four different weight percentage ratios of BA to MMA used in this work were 80:20, 70:30, 60:40 and 50:50. Percentage conversion of the monomer of all latexes prepared was ≥ 79.8 %. The grafting efficiency of grafted natural rubber latexes with a different monomer ratio tended to decrease with an increase of MMA. The adhesion property was characterized by 90° peel strength and 180° lap shear tests. The shear strength value of grafted natural rubber latexes increased with an increase of MMA content. The grafted latex with the monomer ratio of 50:50 possessed higher shear strength than natural rubber latex. The peel strength value of grafted natural rubber latexes seemed to lower than that of natural rubber latex. The weather stability of the modified latex was characterized using thermogravimetric analysis (TGA) and also the peel samples were left in the open air for 45 days before testing. The results showed that grafted natural rubber latex had a higher weather stability than natural rubber latex.