The primary focus of this review is on the cost-effectiveness of critical care. The rapid growth in health care expenditures has engendered careful scrutiny of the practice of medicine with regard not only to effectiveness but also to efficiency. This shift necessitates that physicians understand the effectiveness of their interventions and the cost at which this effectiveness is obtained. Cost-effectiveness and cost-utility analyses have become crucial evaluative tools in medicine. Explicit articulation of comparative cost-effectiveness facilitates the allocation of limited resources. Physicians and policy-makers must evaluate such studies with caution, skepticism, and attention to the methods used.