May-Thurner syndrome (MTS) is a venous compression syndrome in which the left common iliac vein is compressed between the lower lumbar spine and the right common iliac artery. While asymptomatic compression is very common, the process can lead to morbidity in selected individuals, most commonly deep venous thrombosis (DVT) and the sequelae thereof. Radiologists must recognize the diagnosis because of the unique management, which differs from DVT without iliac vein compression.