A simple and reliable method for simultaneous determination of purine and pyrimidine (guanine, adenine, thymine and cytosine) was developed at poly(3,4-ethylenedioxythiophene)/electro-deposited graphene modified glassy carbon electrode (PEDOT/GR/GCE). Scanning electron microscopy and electrochemical impedance spectroscopy were used to examine the morphology and interface property of PEDOT/GR film. Differential pulse voltammetry was utilized to investigate the electrochemical behavior of DNA bases in 0.1 M PBS (pH 7.4). The results showed that the peaks of four bases were well separated. The proposed sensor exhibited low detection limit, high sensitivity and wide linear range for simultaneous detection of four DNA bases, with high stability. (C) 2014 Elsevier B.V. All rights reserved.