Asymmetry is a well known physical feature of scoliosis, expressed as the linear asymmetry of the spinal curvature found in the vertebral column and in other skeletal structures such as the skull and limbs. Fluctuating asymmetry (FA) is a deviation from bilateral symmetry in normally bilaterally symmetrical morphological traits. FA gives a composite reflection estimate of the well-being of an individual in their environment. Developmental stability within a species may be measured in two ways, namely by fluctuating asymmetry where there is a small random deviation from normal and by phenodeviants, where there is a marked deviation from normal developmental traits. The marked deviation from normal development found in idiopathic scoliosis, particularly in growth, is an example of the latter. The present study has examined the relationship between scoliosis and FA in a sample of patients with idiopathic scoliosis. The results indicate that a positive relationship between the degree of spinal curvature and FA with severe curvature being associated with a high degree of FA. These findings indicate that a major phenodeviant (idiopathic scoliosis) is associated with general developmental instability.