Instability of spine is still not precisely defined clinically and its radiological criteria are continually improving and more precise due to development of new imaging methods. The diagnostics is still based on functional X-ray pictures. In the cervical area the finding based on functional X-ray pictures is still rather reliable, but the radiography examination of lumbar spine is complicated, since the mobility of vertebrae in standing position is limited and false negative pictures may be reached. A certain improvement is offered by X-ray pictures in the sitting position. The magnetic resonance imaging represents an important progress in diagnostics. It uncovers traumatic damage of disc-ligamentous apparatus, in an instability of degenerative etiology there are important paradiscal changes of bone marrow according to Modic. Scintigraphy is helpful in differential diagnostics between pseudo-inflammatory changes of the endplate disease type and bacterial spondylodiscitis or in the selection of facet for intervention therapy. It is essential for the diagnostics of spine instability that the clinical finding correlates with imaging methods.

        Key words: spine instability - radiological criteria - functional pictures - magnetic resonance