Background: Hypertension is a chronic disease affecting millions and causing millions of complications every year worldwide. People living with hypertension need to make several lifestyle adjustments, not only for treating hypertension but also for the prevention of other related chronic diseases. Aim: Evaluate the effect of evidence-based lifestyle guidelines on self-efficacy among hypertension patients in Port Said City. Subjects and method:  A quasi-experimental design was utilized for conducting this study. Setting: The study was carried out at primary health care centers located in Port Said City. subjects: A purposive sample of 341 patients with hypertension recruited from randomly chosen six primary health care centers. Tools: Data was collected using three tools, Tool I: Self-Administered Structured Questionnaire divided into three parts namely:   demographic data, patient' medical history, and knowledge assessment sheet, Tool II: Hypertension self-care activities scale and Tool III: Self-efficacy scale. Results: (4.4%) of the study group had satisfactory knowledge in the pre implementation phase while after implementation changed to (94.4%) of them had satisfactory knowledge. Nearly (4.4 %) of them had an adequate level of self-care activity while after implementation become (85.9%). About (2.6%) only had an adequate level of self-efficacy while after implementation become (97.9%). Conclusion: most of studied hypertensive patients had unsatisfactory knowledge, non-adherence to self-care activities and low self-efficacy toward their disease before implementation of evidence-based lifestyle guidelines, while the majority had satisfactory knowledge, adherence to self-care activities and high self-efficacy after implementation of guidelines with highly statistically significant difference. Recommendation: Apply evidence-based lifestyle guidelinesmore and more to cover all hypertensive patients to help them understanding the nature of their chronic disease and trying to cope without complications.