We report the first case of bone marrow cell transplantation to the myocardium of a patient with heart failure due to chagas' disease. The patient is a 52-year-old man with chronic heart failure, NYHA functional class III, despite the optimized clinical therapy. The procedure consisted of aspiration of 50 mL of bone marrow through puncture of the iliac crest, followed by filtration, separation of the mononuclear cells, resuspension, and intracoronary injection. The left ventricular ejection fraction at rest, measured using radionuclide ventriculography with labeled red blood cells prior to transplantation, was 24%, and, after 30 days, it increased to 32% with no change in the medicamentous schedule. The following measurements were assessed before and 30 days after transplantation: left ventricular end diastolic diameter (82 mm and 76 mm, respectively); Minnesota living with heart failure questionaire score (55 and 06, respectively); and distance walked in the 6-minute walking test (513 m and 683 m, respectively). Our findings show that intracoronary injection of bone marrow cells may be performed, suggesting that this is a potentially safe and effective procedure in patients with due to Chagas' disease heart failure.