Background: Promoting patients sense of security is among the goals of nursing care within heart failure management.Objective: The aim of this study was to examine the role of sense of security in the relationship between self-care behavior and health status of patients with heart failure.Methods: Patients recruited from a heart failure clinic in Iceland answered a questionnaire about their self-care (European Heart Failure Self-care Behavior Scale; possible scores, 0-100), their sense of security (Sense of Security in Care-Patients Evaluation; possible scores, 1-100), and their health status (Kansas City Cardiomyopathy Questionnaire, including symptoms, physical limitations, quality of life, social limitations, and self-efficacy domains; possible scores, 0-100). Clinical data were extracted from electronic patient records. Regression analysis was used to examine the mediation effect of sense of security on the relationship between self-care and health status.Results: The patients (N = 220; mean [SD] age, 73.6 [13.8] years; 70% male, 49% in New York Heart Association functional class III) reported a high sense of security (mean [SD], 83.2 [15.2]) and inadequate self-care (mean [SD], 57.2 [22.0]); their health status, as assessed by all domains of the Kansas City Cardiomyopathy Questionnaire, was fair to good except for self-efficacy, which was good to excellent. Self-care was associated with health status (P < .01) and sense of security (P < .001). Regression analysis confirmed the mediating effect of sense of security on the relationship between self-care and health status.Conclusions: Sense of security in patients with heart failure is an important part of daily life and contributes to better health status. Heart failure management should not only support self-care but also aim to strengthen sense of security through positive care interaction (provider-patient communication) and the promotion of patients self-efficacy, and by facilitating access to care.