Ossification and calcification of the spinal ligaments frequently cause pressure upon the spinal cord and nerve roots. Authors reviewed 150 cases of C-spine CT, 80 cases of T-spine CT, and 725 cases of L-spine CT which were carried out at Pusan National University Hospital for 2 years from May 1983 to May 1985. We analysed 34 cases which showed ossification of posterior longitudinal ligament (OPLL) and ligamentum flavum(OLF) of these 955 cases. The results are follows : 1. The male to female ratio of spinal ligamentous ossification was 26 :8 . The 5th decade group(24,41%) was the most prevalent age group. 4th decade (26.4%), 6th decade(23.52%), 7th decade (11.76), 3rd decade (8.8%), and 8th decade(2.94%) in that order. 2. Of 955 cases of spine CT, incidence of OPLL was 25 cases (2.51%) and that of OLF was 10 cases(1.05%). 3. Regional incidence of spinal ligamentous ossification was as follows. 1) In case of OPLL, cervical area was 19/150(12.67%) and lumbar area was 6/725(0.83% . 2) In case of OLF, Thoracic area was 3-80(3.75%) and lumbar area was 8/725(1.10%). 4. The most frequent length of OPLL was 4 body length (32%) and the most frequent locations are C4 and C5 (68%). The types of OPLL were 15 cases (60%) of segmental type, 8 cases (32%) of continuous type, and 2 cases (8%) of mixed type in that order. All segmental types were degree 1 or 2 and most continuous and mixed type (80%) were degree 2 or 3 dural sac effect. 5. The number of involved interlaminar spaces in OLF was 1 to 5 interspaces and most of OLF were found at low thoracic and lumbar area. 6. There could be noted high correlation between the spinal ligamentous ossification and degenerative discdisease. The incidence of associated disc disease was 18/25(72%) in OPLL and and 8/10(80%) in OLF.