To determine if abnormalities exist in postural control in autism and if they are related to age. Dynamic posturography was performed in 79 autistic individuals without mental retardation and 61 healthy volunteers between ages 5 and 52 years. Both the sensory organization and the movement coordination portions of the test were performed. The autistic subjects had reduced postural stability (p = 0.002). Examination of age effects revealed that the development of postural stability was delayed in the autistic subjects (p < 0.001) and failed to achieve adult levels (p = 0.004). Postural stability was reduced under all conditions but was clinically significant only when somatosensory input was disrupted alone or in combination with other sensory challenges (mean reduction in stability of 2.6 +/- 1.0 for the first three conditions without somatosensory disruption vs 6.7 +/- 2.7 for the last three conditions with somatosensory disruption), indicating problems with multimodality sensory integration. The evidence from this and studies of the motor system suggests more general involvement of neural circuitry beyond the neural systems for social behavior, communication, and reasoning, all of which share a high demand on neural integration of information.