Health care resources are limited, and health care providers must strive to maximize health benefits to patients within available resources. This is becoming increasingly important in critical care as demand for services grows and costs associated with treatment increase. Economic evaluations enable comparisons of both the costs and effects of an intervention. There are four main types: cost-minimization, cost effectiveness,cost-utility, and cost-benefit. The costs associated with the intervention are measured in monetary units (dollars); the evaluation types differ with respect to how outcomes are measured. This article introduces the methodology for performing these economic evaluations,highlighting important aspects regarding critical care.