Herein, a simple reduction method for decoration of reduced graphene oxide (RGO) nanosheets with AuPdPt trimetal nanoparticles was developed. The as-synthesized nanocomposite was characterized detailedly using several techniques such as SEM, TEM, FTIR, CV and EDS. The results showed that the trimetal nanoparticles are well dispersed on RGO nanosheets, preventing the serious aggregation and maintaining good electro-catalytic activity. Benefiting from synergistic effect of AuPdPt nanoparticles and RGO, the modified electrode exhibited higher and remarkable oxidation toward retigabine (REG), anti-convulsant drug, with lowered oxidation overpotential. Under the optimum conditions for electrochemical oxidation of REG, the AuPdPt NPs@RGO/GCE displayed a wide linear range of 0.1-40.0 x 10(-7) Mwith LOD of 0.039 x 10(-7) Mif compared to LODs of bare GCE, GO/GCE and RGO/GCE with values of 1.94 x 10(-7) M, 0.32 x 10(-7) M and 0.11 x 10(-7) M, respectively. The main merits of the proposed sensor are the good stability, selectivity and reproducibility which have been successfully applied for the analysis of REG in human plasma and urine samples with good percentage recoveries. The obtained results prove that the proposed sensor could be a promising and convenient material for the construction of reliable and high performance electrochemical sensors. (C) 2019 The Electrochemical Society.