Purpose: To evaluate CT findings of normal anatomic alteration after neck disssection. Materials and methods:The postoperative CT findings were retrospectively reviewed in 40 patients with neck dissection, comparing topreoperative CT. There were 28 patients with radical neck dissection and 12 patients with modified radical neckdissection or selective neck dissection. In addition to the neck dissection, 10 patients had undergone pectoralismajor myocutaneous flap reconstruction, 20 patients taken laryngectomy, and 25 patients treated with radiotherapy.Results: The typical CT findings of radical neck dissection were non-visualization of internal jugular vein andsternocleidomastoid muscle(28/28), ipsilateral neck flattening(26/28), and trapezius muscular atrophy(12/28). Theother non-specific findings were tissue plane effacement, subcutaneous reticular pattern,platysma musclethickening and adjacent soft tissue contrast enhancement which was the only evidence of prevopus operation in thecases of modified radical neck dissection or selective neck dissection. Reconstruction with myocutaneous flap wasshown as ipsilateral bulk of fat and muscle(10/10). In cases with radiation therapy there was much increaseddensity of submandibular gland(12/25). 15 patients showed recurrence on follow up CT scan, including regionalmetastasis in 10, stomal recurrence in two, and residual mass at primary site in three patients. Conclusion: CT isuseful in evaluation of patients with neck dissection and in whom postoperative change impese diagnostic problem.