Increased attention is being focused on the cost of various medical treatments as limited societal resources are recognized. Three-dimensional conformal radiation therapy is a sophisticated technique that allows high doses of radiation to be focused safely on a target. This technique is more expensive to implement and deliver compared with conventional radiation techniques. A consensus, however, is emerging after reviewing the data that shows three-dimensional conformal radiation therapy to be cost-effective when the clinical benefit is most apparent. More data, sophisticated analyses, and follow-up are necessary before more definitive conclusions can be made.