We have undertaken a systematic G-banding survey to find structural chromosomal abnormalities among patients with schizophrenia. Of 120 patients with DSM-III-R schizophrenia, four (3.3%) had a pericentric inversion of chromosome 9 and three (2.5%) had a X/XX mosaicism. The frequency of pericentric inversion of chromosome 9 among patients with schizophrenia was statistically higher than those among newborns and Asian populations. Our results indicate that the pericentric region of chromosome 9 might be one of the potential regions of interest for linkage analysis of schizophrenia.