Autism spectrum disorders (ASDs) constitute a class of severe neurodevelopmental conditions with complex multifactorial and heterogeneous etiology. Despite high estimates of heritability, genetic causes of ASDs remain elusive, due to a high degree of genetic and phenotypic heterogeneity. So far, several "monogenic" forms of autism have been identified, including Rett syndrome, Fragile-X syndrome, and Tuberous Sclerosis, accounting only for a small part of ASDs cases. Further evidences for rare mutations in the etiology of ASDs come from cytogenetic studies. Traditional cytogenetic approaches have highlighted the high frequency of large chromosomal abnormalities (about 7% of patients) and, more recently, the advent of high-resolution oligonucleotide microarrays has made possible to screen genome-wide for structural changes. In this review, we describe less known chromosomal abnormalities reported in association with ASDs and provide some clues to neuropediatricians for a more specific diagnostic evaluation of patients with ASDs. (Contains 2 tables and 3 figures.)