The role of genetic factors in the etiology of the autistic spectrum of disorders has clearly been demonstrated. Ten chromosomal regions, on chromosomes 1p, 4p, 6q, 7q, 13q, 15q, 16p, 17q, 19q and 22q have potentially been linked to autism.1-8 We have analyzed these chromosomal regions in a total of 17 multiplex families with autism originating from the isolated Finnish population by pairwise linkage analysis and sib-pair analysis. Mild evidence for putative contribution was found only with the 1p chromosomal region in the susceptibility to autism. Our data suggest that additional gene loci exist for autism which will be detectable in and even restricted to the isolated Finnish population.