The aim was to review factors affecting patients' access to palliative care. First, the benefits of palliative care for comprehensive care of patients and their families are identified. Despite these benefits, universal standards for access are lacking and referral typically occurs later than is recommended, limiting access to best practice care. Factors relating to access are reviewed in detail. They are grouped conceptually, combining those related to organizational factors, patient, and family-related issues, which include characteristics of patients, preferences for curative care, and willingness to discuss and participate in palliative care, and factors attributed to physicians and health professionals, such as communication styles, sense of efficacy, perceptions of patient readiness, and knowledge of palliative care. Despite the accumulated evidence, the existing studies share methodological weaknesses, which are reviewed. Finally, recommendations for further work in this area are made.