In 1993 a total of 4152 cases of lumbar nerv root compression have been investigated in 11 neurosurgical departments. Beside patient data diagnostics, treatment and course as well as neurological status before and after treatment were subjects of this quality assurance study. Special emphasis was put on a detailed evaluation of complications. In more than 91% surgical treatment has been performed, in 5% of these cases after an attempt of conservative treatment. Nearly 9% of the patients have not been operated upon. Recurrent disease has been treated surgically in 10.5%. Most common procedure was flavectomy (69%) with discectomy (80%). The all over complication rate was 14%. Typical surgical complications have been rare with 5%. Neurological deterioration after treatment was also rare with less than 2%. The study was able to reflect the present state of treatment in patients with lumbar nerve root compression and the subjects investigated served well as parameters of quality assurance.