Unexplored electrochemical behavior of abiraterone, a recent and widely used prostate cancer drug, in interaction with cytochrome P450 3A4 (CYP3A4) enzyme and multi-walled carbon nanotubes (MWCNTs) is investigated in this work. The results reported in this work are significant for personalized medicine and point-of-care chemical treatment, especially to improve the life expectancy and quality of life of patients with prostate-cancer. To this purpose, enzymatic and nonenzymatic electrochemical biosensors were developed and characterized with different concentrations of abiraterone. Nonenzymatic biosensors were functionalized with MWCNTs as catalyst for signal en-hancement, while enzymatic biosensors have been obtained with CYP3A4 protein immobilized on MWCNTs as recognition biomolecule. Enzymatic electrochemical experiments demonstrated an inhibition effect on the CYP3A4, clearly observed as a diminished electrocatalytic activity of the enzyme. Electrochemical responses of nonenzymatic biosensors clearly demonstrated the direct electro-activity of abiraterone when reacting with MWCNT, as well as an electrode-fouling effect.