Objectives. Health-related quality of life (HR-QoL) of patients with heart failure (HF) is low despite the aim of HF treatment to improve HR-QoL. To date, most studies have focused on medical and physical factors in relation to HR-QoL, few data are available on the role of emotional factors such as dispositional optimism. This study examines the prevalence of optimism and pessimism in HF patients and investigates how optimism and pessimism are associated with different patient characteristics and HR-QoL. Methods. Dispositional optimism was assessed in 86 HF patients (mean age 70 +/- 9 years, 28% female, mean left ventricular ejection fraction 33%) with the Revised Life Orientation Test (LOT-R). HR-QoL was assessed with the Minnesota Living with Heart Failure Questionnaire and the EuroQol. Results. The (mean +/- SD) total score on the LOT-R was 14.6 +/- 2.9 (theoretical range 0-24) and the scores on the subscales optimism and pessimism were 8.1 +/- 1.9 and 5.5 +/- 2.5, respectively. Higher age was related to more optimism (r = 0.22, p amp;lt; 0.05), and optimism was associated with higher generic HR-QoL (B = 0.04, p amp;lt; 0.05). Significance of results. The association found between optimism and generic HR-QoL of HF patients can lead to promising strategies to improve HF patients HR-QoL, particularly because the literature has indicated that optimism is a modifiable condition.