We report a systematic appraisal of definitions and approaches to needs assessment in palliative care. Electronic databases were searched, and relevant individuals and organizations were contacted to identify needs assessments in palliative care. Over 200 articles were identified giving general information on needs assessment, and 77 articles comprised palliative care-related needs assessment reports. The reports originated from Africa (37), Australia (1), Europe (including former central/eastern European states) (35), USA (1), Latin America (5), and Asia (7). Two underpinning definitions of need were identified, that of Maslow from the field of psychology, and that of Bradshaw from sociology. However, in conducting needs assessments, these definitions were operationalized, and here the National Health Service Executive definition of need as "the ability to benefit from health care" is helpful. We identified three main categories of approach to needs assessment--epidemiological, corporate, and comparative--that can be used in combination. Careful consideration must be paid to any needs assessment data to ensure that the assessment is implemented.