This study was designed to analyze the clinical presentations and kinematic features in patients with cervical disc herniation at the C3-4 single level. We selected 21 patients with cervical disc herniation at the C3-4 single level who underwent anterior cervical interbody fusion. All the patients had radiographic analysis to evaluate the morphologic characteristics and range of motion at the C3-4 level and the sagittal in order to compare cervical sagittal balance. Clinical symptoms developed in an insidious fashion and included posterior neck pain, occipital pain, shoulder pain, arm pain, and arm numbness. Sixteen patients had myelopathy(72.7%). The mean spinal canal diameter ranged from 9.26mm to 12.87mm(mean, 10.85mm). In comparison with other levels, the spinal canal diameter at C3-C4 was the smallest. The sagittal balance ranged from 31.3 to 69.3 degrees(mean, 47.5 degrees). The C3-C4 segmental range of motion was 16.1 degrees, and it was the largest as compared to other levels. The C3-C4 segmental range of motion occupied 31.7% in total cervical range of motion from C2 to C7. The most important factor in developing cervical disc herniation at C3-4 would be hypermobility, rather than age-related postural change.