Our objective was to measure the incidence of humoral immune response against Trypanosoma cruzi among patients with a definitive diagnosis of dilated cardiomyopathy at the Instituto Nacional de Cardiología "I. Chávez" over a year. Thirty seven patients were collected, 15 of them (40%) had antibodies against T. cruzi in two different tests, indirect immunofluorescence and ELISA, the presence of IgG antibody was confirmed through Western blot. There was not differences in clinical picture of cardiomyopathy nor on paraclinical studies. However, there was a significant difference in regard socio economical indexes between the group with positive anti T. cruzi antibodies. They had a predominant rural origin, poor housing and were aware of the vector bug. Also they recalled primary infection in their childhood--American trypanosomiasis could be on important etiologic factor for dilated cardiomyopathy in our country.