We investigated linkage between schizophrenia and the loci DXYS14, DXYS17, and MIC2 within the pseudoautosomal region in 85 families with two or more siblings suffering from schizophrenia or schizoaffective disorder. A maximum lod score of 2.44 was reached at MIC2, with a dominant model of inheritance at a recombination fraction of 0.367 in females and 0.046 in males (a F: M sex ratio > 1, i.e. opposite to that expected with a pseudoautosomal locus). Evidence consistent with linkage (P = 0.01) was also obtained with a sibling pair analysis at the MIC2 locus. These data do not support (although they do not definitively exclude) a locus within the pseudoautosomal region; they are consistent with the presence of a gene that predisposes to schizophrenia in the sex-specific regions of the X and Y chromosomes.