The simultaneous voltammetric determination of binary mixture containing hydrochlorothiazide (HCTZ) and enalapril (ENP) using a multi-walled carbon nanotubes paste (MWCNTsP) electrode is reported for the first time in the literature. Compared with the glassy carbon electrode or carbon paste electrode, MWCNTsP electrode showed excellent responses for the oxidation of HCTZ and especially for ENP. Square-wave voltammetry was used to simultaneous determination of HCTZ and ENP in their binary mixture in BR buffer solution (pH 5.0), which linear calibration curves were obtained in the range of 4.9 × 10−7–4.5 × 10−5 mol L−1 and 5.0 × 10−6–8.3 × 10−5 mol L−1, respectively. The detection limits were found to be 1.4 × 10−8 mol L−1 and 4.1 × 10−8 mol L−1 for the determination of HCTZ and ENP, respectively. The feasibility of the developed method for real sample analysis was investigated and the accuracy checked from analysis by HPLC.