A novel carbon paste electrode modified with Ni-doped Lewatit FO36 nano ion exchange resin (Ni-LFONRCPE) was fabricated and used as a sensitive electrochemical sensor for simultaneous determination of Epinephrine (EP), Paracetamol (PT) and Tryptophan (TRP). Cyclic voltammetry, electrochemical impedance spectroscopy, differential pulse voltammetry (DPV) and Chronoamperometry methods were employed to study the behavior of EP, AC and TRP on this modified electrode. DPVs peak currents of EP, PT and TRP increased linearly with their concentrations within the ranges of 7-560 mu M, 5-580 mu M and 4-560 mu M with detection limits 0.45, 0.27 and 0.38 mu M for EP, PT and TRP, respectively. The diffusion coefficient (D), electron transfer coefficient (alpha), and heterogeneous rate constant, for oxidation of EP, PT and TRP at the modified electrode surface were also determined. The Ni-LFONRCPE has been applied for the simultaneous determination of EP, PT and TRP in different real samples and the spiked recoveries were in the range of 96-100%.