This study was designed to investigate whether the expression of interleukin 17 (IL-17) is associated with the indeterminate or cardiac clinical forms of Chagas disease and whether IL-17 expression can be correlated with patients' cardiac function. Our results demonstrated that cardiac Chagas patients have a lower intensity of expression of IL-17 by total lymphocytes and lower frequency of circulating T helper 17 cells. Correlative analysis showed that high IL-17 expression was associated with better cardiac function, as determined by left ventricular ejection fraction and left ventricular diastolic diameter values. Therefore, IL-17 expression can be a protective factor to prevent myocardial damage in human Chagas disease.