BackgroundOur understanding of anatomical differences in people with autistic-spectrum disorder, is based on mixed-gender or male samples.AimsTo study regional grey-matter and white-matter differences in the brains of women with autistic-spectrum disorder.MethodWe compared the brain anatomy of 14 adult women with autistic-spectrum disorder with 19 controls using volumetric magnetic resonance imaging and voxel-based morphometry Results Women with autistic-spectrum disorder had a smaller density bilaterally of grey matter in the frontotemporal cortices and limbic system, and of white matter in the temporal lobes (anterior) and pons. In contrast, they had a larger white-matter density bilaterally in regions of the association and projection fibres of the frontal, parietal, posterior temporal and occipital lobes, in the commissural fibres of the corpus callosum (splenium) and cerebellum (anterior lobe). Further, we found a negative relationship between reduced grey-matter density in right limbic regions and social communication ability.ConclusionsWomen with autistic-spectrum disorder have significant differences in brain anatomy from controls, in brain regions previously reported as abnormal in adult men with the disorder. Some anatomical differences may be related to clinical symptoms.