This article describes the relationships between anxiety, self-efficacy, as well as the psychosocial and physiological experiences of patients with an internal cardioverter defibrillator (ICD). Although survival rates with ICDs are impressive, patients experience psychological and physiological responses to their lifesaving devices. Thirty-nine patients completed questionnaires during outpatient clinic visits. Patients' anxiety levels were correlated with fears about ICD malfunction, fear of death, fear of being shocked, loss of control, trouble related to sleeping, inability to concentrate, overprotective family members, and depression. Patients with physical symptoms had higher anxiety levels than those without physical symptoms. There was not a significant relationship between anxiety and discomfort associated with discharge, the number of discharges, or ejection fractions. Low self-efficacy was significantly related to fears about ICD malfunction as well as patients' inability to work, engage in hobbies, and drive a car. Patients with low self-efficacy had more physical symptoms and lower ejection fractions. There were no significant relationships between self-efficacy and frequency of ICD discharge or patients' discomfort during ICD discharge.