Abstract More than one in three people aged 65 years or older fall each year. Between 20% and 30% of those who fall suffer injuries that reduce mobility or hip fracture, and independence and increase the risk of premature death. The study aimed to evaluate the effect of guidelines for fall prevention among elderly people and their informal caregivers. Design: A quasi-experimental study design was used. Setting: The study was conducted at outpatient clinics of Kobry Elkobba Military Hospital. Sample: All targeted elderly aged 65 years old or older in the selected outpatient clinics, with a total number of 110 elderly and their informal caregivers. Tools: Data were collected by using: Tool I: A structured questionnaire about: A) Demographic characteristics of elderly. B) Elderly medical history of chronic diseases C) Prescribed medications and use of walking aids, prior history of falls, and falls-related injuries D) Elderly knowledge regarding the risk of falls, 2) Fall prevention home assessment chart 3) Barthel Index; functional evaluation tool to assess independent activity. Tool 4: Observational sheet of Timed (Up and Go) test, to examine balance of frail elderly and gait speed. Results: The study revealed that, before implementation of the guidelines, 34.5% of the studied elderly had a total correct knowledge score level as regards risk factors of falls of the elderly, which increased to 96.4% after implementing the guidelines, the differences observed were statistically highly significant (X2 = 92.953 at P˂ 0.001). Meanwhile, 40% of their informal caregivers had a total correct knowledge score level in pre-guideline implementation, regarding risk factors of falls of the elderly, which increased to 93.3% after implementing the guidelines, the differences observed were statistically highly significant (X2 = 92.953P at P˂ 0.001).Conclusion: The study findings indicated poor knowledge of the elderly people and their informal caregivers related to prevention and the risk of falling in pre-guidelines, while it improved after implementation of the guidelines. Recommendation: The study recommended health educational programs for the elderly and their informal caregivers related to elderly fall prevention.