<p>  Introduction : Condoliase injection for lumbar disc herniation is less invasive than surgical treatment and has been widely used in recent years. We encountered a case in which a herniated disc worsened after treatment with condoliase (Hernicore^®) injection. Thereafter discectomy was performed. We also report the pathology of the disc removed immediately after condoliase injection.</p><p>  Case presentation : A 34-year-old man with a history of lumbago and left lower extremity pain for 6 months presented to another hospital, wherein magnetic resonance imaging (MRI) showed subligamentous extruded type L5-S1 disc herniation. The patient underwent condoliase injection 3 months after the first visit. However, the patient’s symptoms worsened on the second day after condoliase therapy and did not improve despite the nerve block. MRI showed a transligamentous extrusion-type hernia and substantial compression of the dural sac.</p><p>  Course of treatment : After admission to our hospital, although the patient was administered pregabalin and tramadol, there was no improvement : his preoperative Japanese Orthopaedic Association (JOA) lumbago score was 9/29. Seventeen days after condoliase injection, discectomy was performed to remove the sequestrated herniation. The ventral side of the dural sac was strongly adhered to the disc space. Postoperatively, the patient’s left lower extremity pain improved. However, his lumbago persisted, with a postoperative JOA lumbago score of 15/29. Postoperative MRI revealed Modic type 1 changes in the L5/S1 intervertebral space. His lumbago improved 2 months after surgery, and the Modic type 1 changes disappeared 5 months after surgery.</p><p>  Pathological findings : We compared the excised herniated disc with four aged-matched surgical control cases without condoliase treatment. Toluidine blue staining showed that glycosaminoglycans were substantially decreased in the condoliase-treated discs compared with the control discs. No histological changes in structure were observed.</p><p>  Discussion : In clinical trials, surgery was still required in approximately 10% of cases after condoliase treatment. However, early deterioration after treatment is rare. The pathological findings in the present case indicated that the glycosaminoglycans in the intervertebral disc were degraded early after condoliase administration. Due to the prolonged postoperative lumbago, we considered the possibility of condoliase-induced tissue damage in addition to bacterial discitis.</p>