Purpose: The objective of this study was to evaluate adherence to self-care and identify associated factors in outpatients with Heart Failure (HF). Methods: Using a cross-sectional design, a convenience sample of 249 outpatient clinic patients were recruited at S university hospital. Between October 2009 and December 2009, data were collected through questionnaires and medical record review. Results: The total mean score of adherence to self-care was $18.07{pm}3.56$ out of a possible 45 points. Among self-care dimensions, adherence to medication and low salt diet was high, while lower adherence was reported in contact with health professionals if symptoms such as weight gain, edema and fatigue were presented. Multivariate analysis adjusted for other socio-demographic and clinical factors showed that disease knowledge related to heart failure (p<.001) and left ventricular ejection fraction (p=.027) were independent predictors of adherence to self-care. These factors explained 23% of total variance in the adherence to self-care. Conclusion: Heart failure patients with higher disease knowledge and those who have good systolic function may be more likely to engage in adherence to self-care than those with lack of disease knowledge and low contractility. Further research is needed to confirm these results and identify other predictors of adherence to self-care.