In this study, preparation of a modified carbon paste electrode was investigated for the determination of 17-beta-estradiol (EST) in milk and pharmaceutical samples. Cysteamine self-assembled gold nanoparticle modified fumed silica decorated graphene nanoribbon nanocomposite was used in the modification process. Prepared modified electrode enhanced the electrochemical behaviour of EST by increasing the oxidation peak currents tremendously. Characterization of the prepared electrode was performed by cyclic voltammetry, scanning electron microscopy and Raman spectroscopy measurements. The effects of pH and accumulation time on the electrochemical behaviour of EST were investigated. The effects of possible interfering substances were evaluated. A linear relationship between the oxidation peak currents and EST concentrations was observed between the concentration values of 0.1-5.0 mu M. Relative standard deviation (RSD%) of ten measurements and detection limit were determined as 2.89% and 0.0074 mu M, respectively. The real sample performance of the prepared electrode was evaluated by performing the determination of EST in milk and pharmaceutical samples. The results indicate that the prepared electrode can be safely used in the determination of EST. (C) 2017 Elsevier B.V. All rights reserved.