Several lines of evidence suggest that the sex chromosomes have a role in the expression of schizophrenia. Gender differences in response to treatment, age at onset of illness, and prognosis indicate an influence of sex in differential expression of schizophrenia. On the basis of a higher-than-expected concordance for sex among siblings with schizophrenia, as well as the findings of cytogenetic abnormalities of the sex chromosomes in some schizophrenia patients, a pseudoautosomal location for a schizophrenia susceptibility locus has been proposed. To test this hypothesis, we investigated genetic linkage of the pseudoautosomal region to schizophrenia in a large Swedish kindred. Using pairwise analyses we tested eight markers spanning the most telomeric region to the boundary of the sex-specific region. In addition, we used multi-point analysis with five markers spanning the region to test for the presence of a schizophrenia susceptibility locus in the pseudoautosomal region. No evidence was found for linkage to schizophrenia under the given genetic model: "autosomal" dominant, f (penetrance) = 0.72, q (gene frequency) = 0.02, phenocopies = 0.001.