Morphine is a psychoactive medication that is used as a standard analgesic treatment to relieve pain in clinics. Many patients rely on chronic or acute treatment of morphine to treat pain. However, morphine is a narcotic and has a reverse effect when inappropriately used. Therefore, it is necessary to study chronic and acute morphine treatment to improve pain relief. In this study, differentially expressed genes of acute and chronic morphine-treated mice were identified using Array Express datasets.