BACKGROUND Previous studies have analyzed the role of the genetic polymorphism of endothelial nitric oxide synthase on heart failure prognosis. However, there are no studies relating the G894T and heart failure in Brazil. OBJECTIVE To evaluate the association between G894T GP and the prognosis of a sample of Brazilian outpatients with heart failure. METHODS Cohort study included 145 patients with systolic heart failure, followed for up to 40 months (mean = 22), at two university hospitals, in the State of Rio de Janeiro. We evaluated the relationship between G894T and the following outcomes: reverse remodeling, improvement in functional class (NYHA), and mortality and hospitalization rates. The diameters of the left atrium and ventricle, as well as the ejection fraction of the left ventricle, were evaluated at baseline and at 6 months to assess reverse remodeling. The improvement in functional class was evaluated after 6 months, and mortality rate and hospitalization were evaluated during follow-up. Race was self-declared. G894T polymorphism was analyzed by polymerase chain reaction and restriction fragment length polymorphism. RESULTS The genotypic frequencies were GG (40%), GT (48.3%) and TT (11.7%). The allele frequency was guanine (64.1%) and thiamine (35.8%). There were no differences between the genotype or allelic frequencies according to self-declared race, either as baseline characteristics. There was no relationship between genotype or allele frequency and the outcome measures. CONCLUSION No association was observed between the G894T polymorphism (Glu298Asp) and prognosis in this sample of Brazilian outpatients with systolic heart failure.