Social and behavioral scientists have proposed that a person’s belief system crucially influences his or herbehaviour, and therefore may affect outcomes of pain management. The purpose of this study was to explorethe relationship between analgesic beliefs, analgesic adherence and pain experience amongst Taiwanese canceroutpatients. The cross-sectional study included 92 oncology outpatients in two teaching hospitals in the Taipeiarea of Taiwan. The research instruments included the Pain Opioid Analgesic Beliefs Scale-Cancer (POABSCA),opioid adherence, and the Brief Pain Inventory-Chinese (BPI-Chinese). Beliefs about pain and opioidsdemonstrated a significant relationship with patients’ opioid adherence (r = -0.30, p < 0.01). The more negativebeliefs regarding opioids and pain the patient had, the worse their adherence to around the clock (ATC) analgesicregimen. However, there was no significant correlation between opioid belief and pain experience. As well,there were no significant relationships between adherence to opioid regimen and any of the measures of painexperience. The study highlights the potential importance of a patient’s pain and opioid beliefs in adherence topain medication.