Treatment of spondylolysis and minor form of spondylolisthesis in childhood is usually conservative and includes physical therapy, a temporary reduction in sport activities or the use of an orthosis. Persisting pain despite conservative therapy, neurological symptoms and progressive sliding on x-ray may indicate surgical treatment. We report about the results in 25 patients operated by direct repair of the isthmus between 1982 and 1990 in the Orthopaedic Hospital in Mannheim. In 75% of the cases the special hook-screw by Morscher was used. The other patients were operated according to the original method described by Buck or by the Scott procedure with wire fixation. The clinical and radiological results were available in all patients by a mean follow-up of 8.9 years (4-12 years). All juvenile patients had good or very good clinical results. Within the adult group half of the patients had fair or worse clinical results. Only in 3 out of 14 cases we found bony consolidation of both arches. In 6 cases the x-ray showed pseudoarthrosis on both sides. In 3 of these patients spondylodesis had to be performed. Because of the bad results of direct repair in adult patients, we looked for further criteria, which are necessary to achieve good clinical and radiological results. In addition of the age, the condition of the disc is important. In adolescent patients (more than 16 years old) we documented a degeneration of the disc by NMR or by intraoperative discography.