Abstract: Objective To search for the association between monoamin eoxidases and schizdophrenia,two X-linked microsatellites,(AC)nrepeats at the monoamine oxidase(MAO)A and locus and(T G)nrepeats at the MAOB locus.Mothods PCR was used to study(AC)nrepeats and(TG)n repeats in 140 unrelated Caucasian male patients with schizophrenia and 91 unrelated Caucasiancontrols.Results Allelic frequencies of either(AC)nrepeats or(TG)n repeats were not found to be significantly different between patients and controls.However,a significant excess of the(AC)18/(TG)23 haplotype with a relative risk of 4.05(95% CI 1.15～14.26)was observed in patients with schizophrenia (Fisher’s p=0.011).The coefficient of linkage disequilibrium for the(AC)18/(TG)23 haplotype was 0.019 in schizophrenic patients and-0.046 in controled subjects,respectively.Conclusion The present findings suggested that linkage disequilibrium between polymorphic loci for human MAO-A and MAO-B might be associated with schizophrenia.