Chagas disease (American trypanosomiasis) is caused by the protozoan parasite Trypanosoma cruzi. Chagas disease following solid-organ transplantation has occurred in Latin America, where Chagas disease is endemic, but has not been reported previously in the United States. This report describes three cases in the United States of T cruzi infection associated with transplantation of organs from a single donor. CDC and the U.S. organ transplantation organizations will consider whether to recommend screening of potential donors for T cruzi infection and, if so, which donors to screen, how to screen, and what to do if the screening tests are positive.