Ossification of ligamentum flavum was reported usually lower thoracic and lumbar region, and rarely seen in the cervical region. Calcification of cervical ligamentum flavum is also relatively rare. We report a case of ossification and another of calcification of cervical ligamentum flavum, and discussed the difference of the clinical and radiological features in these conditions. Case 1: A 55-year-old man presented with numbness of the left shoulder and urinary dysfunction. Neurological examination revealed weakness, muscle atrophy and elevated deep tendon reflexes of the left extremities. CT showed ossified mass protruding into the right side of the canal and compressing the spinal cord at C 3/4 and C 4/5. MRI showed low intensity mass both on T1- and T2-weighted images and severe compression of the spinal cord. Left side partial hemilaminectomy with foraminotomy, so called "key hole" foraminotomy, satisfactorily decompressed the cord with clinical improvement. Case 2: A 70-year-old woman complained numbness of both hands for two years. She had sensory disturbance of both hands and spastic gait disturbance. Cervical X-ray films showed calcified nodules on the inner surface of lamina at C4/5. Axial CT demonstrated calcification in the ligamentum flavum at the C4/5 and C5/6 levels. MRI showed posterior spinal cord compression at the C4/5 and C5/6 levels. Osteoplastic laminotomy and removal of the affected ligamentum flavum were performed with successful result. Only 8 cases ossification of cervical ligamentum flavum above C6/7 have been so far reported. All are Japanese; four male and four female cases.(ABSTRACT TRUNCATED AT 250 WORDS)