Unspecific back pain is a common phenomenon. Imaging often shows no clear cause for the genesis of back pain and generally has no impact on the therapeutic procedure. In contrast specific back pain, where a morphological cause is present is more infrequent. In these cases imaging and especially magnetic resonance imaging (MRI) is indicated. The indications for imaging should be geared to the so-called red flags which suggest serious morphological changes of the spine. The article deals with often encountered degenerative changes of the spine and describes spondylodiscitis as an important differential diagnosis to erosive osteochondritis.