Economic evaluations involve the comparison of alternative courses of action in terms of both their costs and their consequences. In response to increasing health care costs, economic evaluations of competing technologies, including radiologic interventions, are increasingly used to inform resource allocation decisions. It is therefore crucial that radiologists have a thorough understanding of the methods. The objective of this paper is to present a detailed overview of the principles and methods of economic evaluations of health technologies, including recent methodologic developments. For the purpose of this paper, the key elements of an economic evaluation are divided into 5 broad sections: 1) types of economic evaluations (eg, cost-effectiveness analysis, cost-utility analysis), 2) study perspectives (ie, temporal and cost perspectives), 3) analysis of costs and effects (eg, incremental cost-effectiveness ratios, cost-effectiveness planes), 4) conducting economic evaluations alongside trials or using decision-analytic models, and 5) dealing with the different forms of uncertainty in economic evaluations (eg, sampling uncertainty in trials, parameter uncertainty in models). Examples from the recent radiology literature are used to explain the key concepts. This review improves upon the previous educational papers published in radiologic journals, as it covers recent methodologic advances regarding the treatment of uncertainty.