OBJECTIVES: Perspective is the point of view from which costs and outcomes of an economic evaluation are evaluated. The results and interpretation of the evaluation depend upon the perspective used. This study evaluates the use of perspective in economic evaluation based on a review of literature, guidelines and current articles. METHODS: A review of the concept and recommended use of perspective in theoretical literature and 31 economic evaluation guidelines was performed. The practical use of perspective was assessed in the 30 economic evaluations published in the Core25 Journals, Health Economics and Pharmacoeconomics in 2004. RESULTS: The use of societal perspective, including all relevant costs and outcomes, was unanimously recommended by the literature and the majority of the guidelines. No source mentioned the possibility and implications of using different perspectives for assessing both costs and outcomes in the same study. All articles reviewed used a different perspective for assessing both costs and outcomes. For assessing costs, the payer perspective was most preferred (22), followed by the societal perspective (4) and other (4). In the case of the outcomes, the patient perspective or outcomes for a patient or person at risk was used a majority of the time (29), followed by family perspective (1). CONCLUSIONS: The findings of different perspectives for assessing outcomes and cost in the same study contradict the conventional wisdom. This affects the interpretation of the results and implications of the study. We recommend the following: 1) explicitly state the perspective used for assessing both, costs and outcomes; 2) the use of the same perspective for both, costs and outcomes; and 3) the sum of individual patient perspectives should not be understood as the societal perspective because it excludes outcomes such as effects on the mental health of patients' families.