Abstract: Bariatric surgeries refer to a group of surgical interventions and are considered the safest and most effective methods of common management of obesity and obesity-related diseases, that lead ultimately to an improvement in the quality of life, as compared to the ways of traditional treatment. Aim: To evaluate the effects of nursing guidelines on postoperative complications and quality of life in patients undergoing bariatric surgeries. Subject and methods: Design: A quasi-experimental design was used. Setting: The study was carried out at the Plastic Surgical Department at Assiut University Hospitals. Sample: A convenient sample of fifty adult male and female patients. The sample was divided into two equal groups (study and control) (25 patients each). Tools: Four tools were used for data collection; patient assessment tool, World Health Organization Quality of Life (WHOQL), and the nursing guidelines for bariatric surgery and complications assessment sheet. Results: There is a good improvement in the overall-knowledge scores of the group of study after implementing nursing guidelines as compared to the control group as well as before guidelines application in both groups. Also, there is a significant reduction in the early and late complications in the study group after applying the guidelines as compared to the other group. In addition, there was a significant improvement in the quality of life of the study group after the intervention of nursing guidelines as compared to the control group with a statistically significant difference was found. While there was no relation between demographic data and health-related quality of life in both groups except for the aged and marital status of the study group. Conclusion: The intervention of nursing guidelines for bariatric surgery patients was effective in improving knowledge, quality of life and reducing the early and late complications postoperative for bariatric surgery patients Recommendation: A printed copy of nursing guidelines is being distributed among patients′ with bariatric surgery, with workshops for nurses being organized for providing them with recent guidelines related to bariatric surgery.