Despite recent advances in our understanding of pain mechanisms, there has been little-to-no overall improvement in the clinical management of postoperative pain. It is now recognized that effective postoperative pain management depends on key predictors, especially patient sex. Preclinical and clinical data indicate that, while postoperative pain levels show little-to-no sex-dependent dimorphisms, there are significant sex-based differences in analgesic efficacy, safety profile and abuse/addiction potential of current drugs used to treat postoperative pain.