A voltammetric sensor was proposed for simultaneous determination of paracetamol and diclofenac based on poly (L-arginine)/Au-graphene nanocomposite film deposited on a glassy carbon electrode. Cyclic voltammetry showed that paracetamol and diclofenac provided well - defined oxidation peaks at +0.443 and +0.644 V, respectively. Experimental parameters, such as the concentration of L-arginine and number of potential cycles in electro-polymerization step, accumulation potential and time, and the pH of buffer solution were optimized. Under the optimized conditions, linear relationships between oxidation peak current and concentration in the range 0.5 – 50.0 μM for paracetamol, and 0.5 – 40.0 μM for diclofenac were obtained in linear sweep voltammetry regime. The limits of detection (LOD) for paracetamol and diclofenac were 0.04 and 0.08 μM, respectively. The fabricated electrode exhibited good reproducibility and stability. The proposed method was successfully applied to the assessment of low concentrations of paracetamol and diclofenac in spiked human blood serum samples with satisfactory results.