In situ synthesis of gold nanoparticles on poly (L-arginine) modified glassy carbon electrode using poly (L-arginine) as reduction agent is reported. EDAX pattern suggests that the gold nanoparticles can be in situ synthesized on poly (L-arginine) modified glassy carbon electrode. SEM image shows that the gold nanoparticles are well dispersed on the surface of glassy carbon electrode. The as-synthesized gold nanoparticles show excellent electrocatalytic activity for the oxidation of glucose. This strategy provides an in situ approach to prepare gold nanoparticles modified electrode using poly (amino acid) as reduction agent for sensor and catalytic applications.