While an increased incidence of scoliosis in symptomatic spondylolysis and spondylolisthesis has been established previously, a comparison of its occurrence in symptomatic and asymptomatic individuals has not been performed. The present study is a comparison of symptomatic and asymptomatic young men with analysis as to the incidence of scoliosis. Idiopathic scoliosis was not found and all cases were due to spasm scoliosis or olisthetic scoliosis with the spasm type being much more common. Scoliotic curves were divided into mild (0-9 degrees) and moderate (10-20 degrees). No case of a curve greater than 20 degrees was seen. Scoliosis incidence in asymptomatic individuals without a pars break was 6.65%. In the groups of: (1) asymptomatic unilateral spondylolysis, (2) asymptomatic bilateral spondylolysis, (3) symptomatic bilateral spondylolysis, and (4) asymptomatic spondylolisthesis the scoliosis incidence was similar, ranging from 13.3-23.8%. These figures are significantly higher than those seen in the asymptomatic subjects without a pars break, but they are in the same range as in symptomatic patients without a pars break, suggesting that muscle spasm is the principal cause of the scoliosis.