Background: Leg edema is a common symptom among elderly patients with multiple underlying diseases. This study was aimed to investigate the etiologies and underlying diseases of leg edema in elderly patients.Methods: We retrospectively reviewed medical records of 247 patients aged over 65, who visited an Emergency Department of a tertiary hospital due to leg edema from January 2010 to December 2012. Results: A total of 226 patients with complete medical records were included. The most common cause of leg edema in elderly patients was renal failure (42 cases, 18.6%), followed by heart failure (37 cases, 16.4%), and deep vein thrombosis (32 cases, 14.2%). However, the etiologies were not established in 66 cases (29.2%). Patients with leg edema caused by renal and heart failure had renal (40 cases, 95.2%) and cardiovascular diseases (29 cases, 78.4%), respectively, while others had diabetes mellitus and trauma. Patients with leg edema caused by deep vein thrombosis had underlying conditions such as cancer (13 cases, 40.6%), trauma, surgery within 1 year, and diabetes mellitus. Overall, chronic bilateral edema (120 cases, 53.1%) was most commonly observed form of leg edema in elderly patients. Deep vein thrombosis, cellulitis, and lymphedema usually caused unilateral edema, whereas systemic diseases such as renal failure, heart failure, and liver cirrhosis caused bilateral edema. Conclusion: Leg edema in elderly patients is usually caused by systemic diseases such as renal and heart failure closely related to underlying diseases. Therefore, it is important to consider the variety of underlying diseases, when approaching the cause and treatment of leg edema in elderly patients.