Background: Open heart surgery is a source of high levels of emotional distress for the patient. If the stress experienced is not adequately compensated, it could harm the postoperative recovery and could not be treated the comorbid mental disorders. Open heart surgery could be a traumatic and stressful experience, and as a result, many people experience psychological difficulties following treatment. Post-Traumatic Stress Disorder (PTSD) is now being investigated in the post-surgical population with surprising results. Open heart surgery is a common intervention that involves several pain-sensitive structures, and intense postoperative pain is a predictor of persistent pain. The study aimed to investigate the effect of a nursing intervention on fear, post-traumatic stress symptoms, and pain among patients with Open heart surgery Setting: The study was conducted at the open heart surgical department and open heart surgical intensive care unit at Menoufia University and Shebin elkom teaching hospitals, Menoufia Governorate, Egypt. Sample: Purposive sample of 80 patients with open heart surgery were enrolled from the previously above-mentioned settings. Data collection: Four tools were used; a semi-structured interview questionnaire, Surgical Fear Questionnaire (SFQ), Davidson Trauma Scale-DSM-IV, and The Numeric Rating Pain Scale Results: Results revealed that there was no significant difference between the study and the control groups regarding demographic characteristics (p>0.05). Also, results revealed a highly significant improvement (with p < 0.0001, in mean surgical fear, pain, and post-traumatic stress symptoms). Conclusion: It was concluded that overall, preliminary findings support the positive effect of the nursing intervention in treating people who have undergone open-heart surgery. Where nursing intervention reduces fear, post-traumatic stress symptoms, and pre and postoperative pain. Recommendations: The developed nursing intervention should be carried out pre and postoperative to reduce fear, post-traumatic stress symptoms, and pain among all patients undergoing open-heart surgery.