Trypanosoma cruzi amastigotes derived from fibroblast cultures and from cell- free liquid mediun were comparatively evaluated as solid-phase of Elisa for Chagas' disease. Amastigotes were obtained from the high- and low-virulent clones of the Talahuen strain and fron the G-1 strain. They were sonicated and directly applied into wells of a microplate to use insoluble particles as antigens. Fifty-one sera from patients of Chagas' disease including one acute caes (Romaña's sing), 10 sera from patients of cutaneous leishmaniasis including one serun of midex infection with Chagas' disease, and 10 sera from patients of toxoplasmosis including three of mixed infection with either Chagas' disease or Leishmaniasis were examined. All amastigotes from different sources and from different clones or strains showed considerable correlation with each other. Slightly higher sensitivity was found in amastigotes of high-virulent clones and slightly higher specificity in those from cell-free culture. One acute case was detected as positive by these methods although it was negative by the usual Elisa using epimastigotes