Background: Heart failure continues to increase in prevalence with a great impact on morbidity and mortality. Aim: To evaluate the effect of applying designed nursing guidelines on health outcomes among patients with heart failure class III. Research design: Quasi-experimental (pre & post assessment) design. Setting: The study was carried out in the Inpatient Cardiology Department at Al-Azher University Hospitals & affiliated Outpatient Cardiac Clinic. Sample: A purposeful sample of (30) patients their ages ranged from (20–75) years old from both sexes. Tools: tool (1): Patient Structured interview questionnaire. Tool (II): Dutch Heart Failure Knowledge Scale. Tool (III): Structured Outcomes Assessment of Patient with Heart Failure. Results: there was statistical significant difference as regarded total knowledge score level, diet categories & red, yellow zone exacerbation signs and symptoms of the study sample in relation to all items in pre & post nursing guidelines with P. value < 0.001 Conclusion: significant improvement in health outcomes among patients with heart failure class III post nursing guidelines application in form of dietary modifications, knowledge improvement, reduce worsen exacerbating signs & symptoms. Recommendation: Study risk factors associated with preventable heart failure exacerbations at regular intervals after hospital discharge