Enzymes of the cytochrome P450 (CYP) superfamily are the major determinants of half-life and execute pharmacological effects of many therapeutic drugs. In new drug discovery research, recombinant (human) CYPs are also used for identifying active or inactive metabolites that could lead to increased potency or toxicity of a molecule. In addition, CYP inhibition by anticancer drugs might lead to adverse drug reactions, multiple-drug resistance, and drug-drug interactions. During the discovery and pre-clinical evaluation of a New Chemical Entity (NCE), large amounts of purified recombinant CYPs are required for studying metabolism and pharmacokinetic parameters. Therefore, present research efforts are focused to over-express these human CYPs in bacteria, yeast, insect and mammalian cells, followed by their purification on an industrial scale to facilitate identification of novel anticancer drugs. This review summarizes the merits and limitations of these expression systems for an optimized production of individual CYP isoforms, and their usefulness in the discovery and development of target-based, safe and efficacious NCEs for the treatment of cancer.