This study demonstrates that infection of the retro- and intradiscal space is probable, when the temperature rises above over 37 degrees and CRP exceeds 2.0 mcg/ml 5 days postoperatively. MRI of 4 patients confirmed a retrodiscal infection that was indicated by a hyperintense band shaped structure in PS-sequences and which was space occupying with respect to the dural sac. Discitis was demonstrated by intradiscal hyperintensity in STIR images and by enhancement in T1 weighted images following the application of Gadolinium DTPHA. Diagnosis is simplified by comparison of pre- and postoperative MR-examination. Infection can be cured by treatment with antibiotics (Tobramycin and Clindamycin) bedrest and plaster cast.