Chagas disease was described in Mexico by Mazzotti in 1940. Post-transfusional cases have not been described. We report proved case of acute chagasic cardiopathy in a nine months old infant with suspected transfusional infection during neonatal period. She was treated with nifurtimox with disappearance of parasites and regression of cardiopathy. She is asymptomatic nine years afterwards with normal growth and negative parasitology and serology.