Upper extremity deep vein thrombosis (UEDVT), though less common than the corresponding disease of the lower extremity, is an important clinical entity because of its potential for higher morbidity and even mortality from pulmonary embolism and occult malignancy. Herein we report on a 59-year-old man who presented with significant swelling of the left upper extremity. UEDVT was diagnosed and treated without significant complications. Although UEDVT is rare, it has become more common over the past several decades because of the increasing use of central venous catheterization and increased life expectancy resulting from medical improvements. Physicians are therefore required to understand this illness to provide a timely diagnosis and adequate treatments.