The association between spondylolisthesis and scoliosis was studied in 84 patients who presented during a 30-year period with symptomatic spondylolisthesis. The incidence of scoliosis was 42 per cent, the majority of cases being lumbar or thoracolumbar curves of less than 15 degrees. The incidence was highest in the group of patients with spondylolisthesis at L4--5 where all except one had scoliosis. Scoliosis was present in 47 per cent of patients with dysplastic spondylolisthesis at the lumbosacral junction; in this group, the incidence of scoliosis was greater where the displacement exceeded 25 per cent. The lowest incidence (25 per cent) was found in the group with isthmic spondylolisthesis at the lumbosacral junction. There appeared to be no relationship between excessive lumbar lordosis or tightness of the hamstrings and scoliosis.