The authors describe the case of a 58-year-old man with a 6-month history of severe myelopathy. CT scan and MRI of the spine revealed a cystic formation, measuring about 1 cm in diameter, at C7-T1 at a right posterolateral site at the level of the articular facet. At operation the mass appeared to originate from the ligamentum flavum at the level of the articular facet and was in contact with the dura mater. Once the mass had been removed, there was a significant amelioration of the patient's symptoms. As previously suspected, histological aspect was synovial cyst. Cervical synovial cysts are extremely rare and, as far as we know, only 22 cases have so far been described in the literature. Diagnostic radiological investigations used were CT scan and MRI. At CT scan the most important diagnostic findings are a posterolateral juxtafacet location of the mass, egg-shell calcifications on the wall of the cyst, and air inside the cyst. At MRI the contents of the cyst are iso/hypointense on T1- and hyperintense on T2-weighted images. There may also be a hypointense rim on T2-weighted images, which enhances after i.v. administration of gadolinium. Surgical treatment consists of removal of the mass. Fixation of the vertebral segments involved is not always necessary.