An electrochemical sensor based on multi-walled carbon nanotubes and chitosan-nickel complex (MWCNTs/CIS-Ni) was fabricated by self-assembly technique for sensitive determination of metronidazole. The electro-analytical performance of the proposed MWCNTs/CTS-Ni modified electrode was intensively evaluated. The experimental results indicated that the MWCNTs/CTS-Ni modified glassy carbon electrode exhibited excellent electrocatalytic activity towards metronidazole. The proposed sensor revealed linear response to metronidazole in the concentration range of 0.1 to 150 pmol L-1, with a low detection limit of 0.025 mu mol L-1. Moreover, the sensor also showed good selectivity, reproducibility and stability. The proposed method could be successfully applied for the sensitive determination of metronidazole in pharmaceutical and biological samples.