Only little is known about the interrelation of scoliosis and spondylolysis-spondylolisthesis. Basically we may differentiate between scoliosis due to spondylolisthesis and spondylolisthesis probably due to scoliosis, with several subunits. Scoliosis due to spondylolisthesis is based on an asymmetrical forward shift of the fifth vertebra on the sacrum combined with one segment tilted. This results in a local instability with a compensatory lumbodorsal curve potentially becoming structural. The existence of a spondylolysis due to a dorsolumbar scoliosis is postulated on the basis of several observations, though no personal statistical data are available: In the presence of an idiopathic lumbodorsal scoliosis one encounters more frequently than expected an unilateral spondylolysis. On the other hand one may observe healing of the interarticular process of the laminae following the correction and fusion of a dorsolumbar scoliosis as occasionally seen with cast treatment of spondylolysis in children. Lumbar spondylolysis may create a progressive lumbar scoliosis even in early adulthood. The primary disease, may it be scoliosis or spondylolysis-spondylolisthesis, has to be treated according to its own rules conservatively or by operative fusion. The secondary disease requires treatment only if it becomes severe or painful.