A locus for schizophrenia within the pseudoautosomal region of chromosomes X and Y has been suggested by Crow on the basis of epidemiological data. The present report replicates this finding in a sample of 38 French multiply affected families with schizophrenia. Sibship and pairwise analysis, with or without weighted-pair correction, with three different systems of family classifications, showed there to be an excess of same-sex pairs in paternally derived sibships, as predicted by the pseudoautosomal hypothesis.