Radiographic measurement of cervical spine is very important in cervical spine injury especially those without fracture. Authors measured the retropharyngeal space, retrotracheal space, lordortic curve and sagittal diameter of cervical spinal canal in 148 cases of normal adult male. The results are as follows: 1. In normal Korean adult male maximum retropharyngeal space is 7mm in C, level and Smm in Cs level. Maximum retrotracheal space is 16mm in C, level. 3. Loss of normal lordotic curve is shown in 21 cases(14.2%), 4. Average sagittal diameter of C, level is 21.27mm-it’s the largest of all the cervical spinal cana1s, and that of C, level is 16.15mm-it’s the smallest.