The purposes of this study were as follows: (1) to compare the attitudes which were considered to be barriers to cancer pain management held by Taiwanese cancer patients and their family caregivers; (2) to determine if these barriers were related to patient hesitancy to take analgesics and/or family caregiver hesitancy to administer analgesics: and (3) to determine if attitudinal barriers by patients and/or family caregivers predicted the adequacy of analgesics that patients used. A total of 159 dyads of oncology outpatients and their primary family caregivers (n = 318) participated in this study. The instruments completed by patients consisted of the Barriers Questionnaire-Taiwan form, the Brief Pain Inventory-Chinese version, the ECOG performance status scale, and a demographic and medication questionnaire. Family caregivers completed the Barriers Questionnaire-Taiwan form and a demographic questionnaire. The data in this study revealed that patients and family caregivers had attitudinal barriers to pain management and these concerns were positively correlated between patients and caregivers. Patient concerns were related to their hesitancy to take analgesics and, similarly, caregiver concerns were related to their hesitancy to administer analgesics. Most importantly, patient and caregiver concerns had an impact on how the patients' pain was managed: (1) patients and their family caregivers with higher levels of concerns used inadequate analgesics as compared to patients using adequate analgesics; (2) family caregiver barriers (concerns) were a significant predictor of inadequate management of cancer pain (after controlling for demographic and disease variables). Therefore, educational interventions for overcoming these barriers for both patients and their family caregivers may have potential for improving the management of cancer pain in Taiwan.