Many cases of autism appear to be caused by several abnormal genes acting in concert. The literature on chromosomal aberrations in autism is reviewed, with a view to finding potential gene markers for the neuropsychiatric disorder. Most of the chromosomes have been implicated in the genesis of autism. However, aberrations on the long arm of Chromosome 15 and numerical and structural abnormalities of the sex chromosomes have been most frequently reported. These chromosomes appear to hold particular promise in the search for candidate genes.