A screen printed electrode functionalized with multi-walled carbon nanotubes and factory modified with carboxyl groups (MWCNT-COOH/SPCEs) was characterized by cyclic voltammetry and differential pulse voltammetry in a NaCl (0.1 mol L-1, pH 7) solution containing 800 μmol L-1 sodium dodecyl sulfate (SDS). The MWCNT-COOH/SDS/SPCEs sensor was tested for the detection and quantification of cisplatin. For solutions of cisplatin, the electrochemical analysis showed a linear correlation coefficient of 0.9974 to cisplatin at concentrations between 1.45 × 10-5 and 1.0 × 10-4 mol L-1, a sensitivity of 4.4 × 104 (±1.0 × 103) μA L mol-1, and detection and quantification limits of 4.6 × 10-6 and 1.4 × 10-5 mol L-1, respectively. The reproducibility of the sensor response evaluated by the analysis of three replicates, indicated a RSD of 3.91%. The excellent response of the MWCNT-COOH/SDS/SPCEs cisplatin sensor allowed it to be tested in samples of human blood serum whose levels of added cisplatin were monitored by the HPLC. The average error % (sensor/HPLC) of 3.4 indicates that the combined methodology of MWCNT-COOH modified SPCE and the addition of a surfactant such as dodecyl sulfate is a convenient alternative for the use of HPLC for cisplatin determination in biological samples. The methodology cannot be applied to non-ionizable antitumor drugs carboplatin, oxaliplatin, doxorubicin or gemcitabine.