The purpose of this study was to assess the potential inhibitory and inductive effects of felotaxel on cytochrome P450 isozymes in vitro. The inhibitory effects of felotaxel on various CYP isozymes were determined in human liver microsomes. In addition, the ability of felotaxel to induce CYP enzymes in cultured human hepatocytes was evaluated. Results showed that felotaxel did not inhibit CYP1A2-, CYP2C9-, CYP2C19-, CYP2E1-, CYP2D6-, CYP2B6-, CYP2C8-, and mediated activities in human liver microsomes up to a concentration of 100μM, while the inhibition (<30% inhibition) of CYP3A4 activities was observed at 100μM felotaxel. In vitro felotaxel did not induce CYP1A2, CYP2C19, or CYP3A4/5 activities in cultured human hepatocytes. In present study, felotaxel has been identified as a potent inhibitor of metabolic activity of CYP3A4. Therefore, clinically relevant pharmacokinetic drug–drug interactions are likely to occur between felotaxel and co-administered substrates of these CYP3A4 isozymes. These findings provided some useful information for safe and effective use of felotaxel in clinical practice.