A new home-made screen-printed carbon electrode (SPCE) modified with a functionalized multiwalled carbon nanotubes (MWCNTCOOH) and benzyl acetate (BA) was prepared for electrochemical determination of sulfasalazine (SSZ). Determination of SSZ was carried out by differential pulse voltammetry (DPV) in 0.04 mol L-1 Britton-Robinson buffer solution of pH 1.7 at -40 mV (versus Ag/AgCl) at MWCNTCOOH/BA-SPCE. The electrochemical behavior of the modified SPCEs was investigated by cyclic voltammetry and impedance spectroscopy. The effects of various parameters on the response of the electrode such as type of modifier, pH of the buffer, and DPV parameters were investigated. The reduction peak current obtained from DPV of SSZ increased linearly with its concentration at the ranges of 1.0-14 mu mol L-1 and 14-70 mu mol L-1 with sensitivities of 1.84 and 0.48 mu A mu M-1 cm(-2). The relative standard deviation (RSD%) of seven replicates of current measurements for a 20 mu mol L-1 of SSZ solution was 3.2%. The detection limit of the method was found to be 0.3 mu mol L-1. The prepared sensor was successfully applied for the determination of SSZ in pharmaceutical formulation and biological fluid samples. (C) 2014 Published by Elsevier B.V.