Although health care expenditure has increased steadily over the past decennium, the general feeling is that resources are more limited than ever. One reason for this may be that the range of treatment options has grown so wide that the need to make rational choices has become apparent. Since treatments vary with respect to both effectiveness and cost, economic evaluations are becoming an important tool for assessing new and existing treatment strategies. The basic concepts of economic evaluation will be introduced here and the key economic questions with respect to treatment of fungal infections in cancer patients identified. Some of these concepts are explained using findings from a pilot survey carried out among participants in the symposium "Trends in Invasive Fungal Infections-3" 7-9 held September, 1995, in Brussels, Belgium. The conclusion will offer recommendations for assessing economic evaluations.