Obesity is a major public health problem affecting all ages in both developed and developing countries. It is considered the fifth leading risk factor for deaths all over the world as about 2.8 million people die due to obesity each year directly or indirectly. Obesity in elderly is considered one of the most serious public health challenges for all over the world. It is a complex; multifactorial disease arises from the interactions between genetic, environmental and behavioral factors together with other factors results in energy imbalance and promotes excessive fat deposition. Aim: to Determine Prevalence and Risk Factors of Obesity among Elderly attending Geriatric Outpatient Clinics in Mansoura City. Method: Descriptive, analytical, cross sectional hospital based research design was used. The study carried out on 126 elderly attending Geriatric outpatient clinics in the specialized medical hospital and general hospital in Mansoura City. Data was collected using 3 tools, sociodemographic and clinical data structured interview sheet, Health promoting Lifestyle profile II (HPLPII), Body Mass Index. Results: The results indicate that the prevalence of obesity among elderly attending Geriatric Outpatient Clinics in Mansoura City was 33.3% and there was significant relation between positive family history of obesity, unhealthy lifestyle as poor nutritional habits, and lack of physical activity, poor stress management and obesity. Conclusion: Increase awareness about obesity and healthy lifestyle is essential for elderly to prevent obesity and its complications.