CYP 2C8, which carries out the oxidative metabolism of at least 5% of clinical drugs, has attracted increasing attention in recent years. New drugs (substances), inducers and inhibitors of CYP 2C8 have been developed and the drug metabolism has been investigated to understand the clinical role of CYP2C8. The cases of CYP2C8 genetic polymorphisms linked to diseases have increased and have been investigated. Herein, important progress in these areas has been reviewed with an emphasis on drug metabolism. Polymorphisms, diseases related to CYP2C8, some important drugs (substances) and inhibitors are reviewed and discussed.