Few reports so far in literature has discussed misdiagnosis of Zenker's diverticulum, and its features of both ultrasound (US) and computed tomography (CT) scanning. We report a case of Zenker's diverticulum misdiagnosed as thyroid adenoma confirmed in operation, and discuss features of its US and CT images, analyze reasons for misdiagnosis. Strong echogenic foci caused by air is the most important features of ultrasonic images; identification of existence of air within the foci and unclear border between nodule and esophagus are the most common presentations of CT scanning, which is the main point of its differential diagnosis from thyroid nodules. Not fully aware of such images is the main reason for misdiagnosis. These image findings should be well understood by both US/CT doctors and surgeons to prevent unnecessary operation.