OBJECTIVE: Catechol O-methyltransferase (COMT) is involved in the degradation of catecholamine neurotransmitters. Recent linkage studies of schizophrenia and molecular studies of velocardiofacial syndrome suggest that the COMT gene might be a candidate gene for schizophrenia. METHOD: The authors systematically searched for mutations and microdeletion of the COMT gene in 177 Chinese schizophrenic patients from Taiwan; 99 comparison subjects were also studied. RESULTS: Five molecular variants were identified: c.186C>T at exon 3, c.408C>G at exon 4, c.472G>A at exon 4, c.597G>A at exon 5, and c.821-827insC at the 3′ untranslated region. However, no differences in the genotype and haplotype frequencies of these molecular variants between the schizophrenic and comparison subjects were detected. Furthermore, no microdeletion was identified among the patients. CONCLUSIONS: These data suggest that the COMT gene does not play a major role in the pathogenesis of schizophrenia, and the genotypic overlap between schizophrenia and velocardiofacial syndrome was rare in this cohort.