A novel electrochemical sensor based on the functionalized multiwalled carbon nanotube (f-MWCNT) was successfully developed for the sensitive and selective determination of non-steroidal prostate anti-cancer drug nilutamide in tablet and blood serum samples. The f-MWCNT was prepared by the simple reflux method and characterized by the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, X-ray powder diffraction (XRD) and fourier transform infrared spectroscopy (FT-IR). Interestingly, the f-MWCNT was exhibited a superior electrocatalytic activity towards the anti-cancer drug nilutamide when compared with pristine MWCNT and unmodified electrodes. Besides, the electrochemical sensor was revealed an excellent current response for the determination of nilutamide with wide linear ranges (0.01-21 mu M and 28-535 mu M), high sensitivity (11.023 and 1.412 mu A mu M-1 cm(2)) and very low detection limit (LOD) 0.2 nM. The developed electrochemical sensor was showed an excellent selectivity even in the presence of electrochemically active biological substances and nitro aromatic compounds. Moreover, it manifested a good reproducibility and stability. In addition, the f-MWCNT modified glassy carbon electrode (GCE) sensor was successfully applied for the detection of nilutamide in tablet and blood serum sample. (C) 2016 Elsevier Inc. All rights reserved.