New therapies, such as nanotechnology-based cancer treatments, typically entail high acquisition costs. Their use can be justified, however, by their superior cost–effectiveness. This article assesses the quality of cost–effectiveness analyses of nanotechnological cancer therapies by screening nine major studies. They conclude that nanotherapies are cost effective for the treatment of ovarian and breast cancer, as well as multiple myeloma, but not for other types of cancer. However, these studies have some serious methodological flaws. Typically, the results are not quality adjusted, although both length and quality of life are affected. Moreover, only fragmented direct medical costs are included, neglecting indirect costs that impose a significant economic burden on patients and society. Finally, cost definitions differ widely making any comparison between studies virtually impossible. This article concludes that economic research of nanotechnology-based therapeutics is still in its infancy. It warns that incomplete economic analysis may lead to inefficient policy recommendations.