Autism and Asperger's disorder (AD) are characterised by impairments in social interaction, stereotypic behaviours or restricted interests. Although currently listed as distinct clinical disorders, the validity of their distinction remains controversial. This study examined gait in children with autism and AD. Eleven children with high-functioning autism and eleven children with AD completed a series of walking tasks. Results indicated distinct movement disturbance; these findings are discussed in light of seminal papers in this field by Vilensky et al. (Arch Neurol 38:646-649, 1981) and Hallett et al. (Arch Neurol 50:1304-1308, 1993) who interpret the gait of individuals with autism using parkinsonian and cerebellar-ataxia patient models, respectively. Distinctions in gait patterns implicating perhaps unique motor circuit disturbances support the hypothesis that autism and AD may have unique neurodevelopmental trajectories.