Measure: ment of normal value of the SAC (Space Available for the Cord) is very important to find the diagnostic criteria and the optimized treatment of the Cervical Spinal Stenosis in Viet Nam. Objectives: Measure normal value of the SAC from C3 to C7 of Vietnammese population from 20 to 60 years old. Methods: Measure the SAC on 300 persons from 20 to 60 years old by MRI Resultls: The mean SAC of Vietnammese population from 20 to 60 years old are demonstrated: C3: 5.2 + / - 1.5 mm, C4: 5.1 + / - 1.5 mm, C5: 4.9 + / - 1.4 mm, C6: 5.2 + / -1.6 mm, C7: 6.5 + / - 1.5 mm. Conclusion: The result of study is basic for other morphological and pathological studies of the Cervical Spinal Stenosis in Vietnammese population.