Background: Given the importance of improving health for patients with heart failure, the present study examined the temporal associations between eHealth literacy, insomnia, psychological distress, medication adherence, quality of life and cardiac events among older patients with heart failure. Methods: With a longitudinal design older patients with echocardiography verified heart failure (N=468; 50.4% New York Heart Association class II, mean age 69.3 +/- 7.3 years; 238 men) in need of cardiac care at seven Iranian university outpatient clinics went through clinical examinations and completed the following questionnaires at baseline: eHealth literacy scale (eHEALS, assessing eHealth literacy); 5-item medication adherence report scale (MARS-5, assessing medication adherence); Minnesota living with heart failure questionnaire (MLHFQ, assessing quality of life); insomnia severity index (ISI, assessing insomnia); and hospital anxiety and depression scale (HADS, assessing psychological distress). All the patients completed the ISI and HADS again 3 months later; and the MARS-5 6 months later. Also, their cardiac events were collected 18 months later. Three mediation models were then conducted. Results: eHealth literacy had direct and indirect effects (through insomnia and psychological distress) on medication adherence and quality of life. Moreover, eHealth literacy had protecting effects on cardiac events (hazard ratio (HR) 0.53; 95% confidence interval (CI) 0.37, 0.65) through the mediators of insomnia (HR 0.19; 95% CI 0.15, 0.26), psychological distress (HR 0.08; 95% CI 0.05, 0.12) and medication adherence (HR 0.05; 95% CI 0.04, 0.08). Conclusion: As eHealth literacy was a protector for patients with heart failure, healthcare providers may plan effective programmes to improve eHealth literacy for the population. Additional benefits of improving eHealth literacy in heart failure may be decreased insomnia and psychological distress, improved quality of life, as well as decreased cardiovascular events.