A framework for economic evaluations of new interventions for the control of Chagas' disease depende upon the comparison to be madeinterventions in different sectors, within the same sector, or for a given objective in the control of a single disease. For comaprisons between sectors, the relevant framework is that of cost-benefit analysis, but ther are difficulties in measurinf the benefits in the helath sector. Within the health sector the suggested comparison is between the present values of streams of costs and discounted productive years of helathy life saved by different interventions. The nature of the transmissión of Chagas' disease is such as to suggest that the comparison should be between the present values of steams of costs to achieve a given objective ine ach year. The relevant cost concept is that of social opportunity cost and teh preferred comparison is between present values of streams of costs corrected for overvalued eschange rates, market distortions and inflation