About 10% of lumbar disc herniations are localized in an extreme lateral position referred to as "extracanalicular". The clinical syndrome is a typical one with compression signs of the lateral, extra-foraminal nerve root and minimal lumbar pain. A reliable diagnosis can be made only since high resolution spinal computed tomography has become available. Surgical treatment will be rendered difficult by the "hidden" localisation of the disc fragments. A total number of 15 patients has been operated on in our department during the last year. In 10 patients, we used the lateral microsurgical approach proposed by REULEN, in five cases a combined procedure with lateral sequestrotomy and medial nucleotomy. In the first group, re-sequestration occurred in three cases and further surgery including medial nucleotomy was performed then. A good result with remission could be achieved in 13 cases, whereas in two cases with additional spondylolisthesis, lumbar back pain continued, but the radicular symptoms were reduced.