Abstract Several studies have reported associations between catechol- O-methyltransferase (COMT) gene Val158Met polymorphism and P300 event-related potentials in schizophrenic patients. But there has been no research to study the association between the P300 component and the Val158Met polymorphism in Chinese Han schizophrenia patients. Therefore, the present article was aimed at investigating the relationship of the Val158Met polymorphism with P300 in Chinese schizophrenic patients. The Val158Met polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 287 schizophrenia patients and 84 healthy control subjects. P300 recordings were obtained in a subsample. A significant difference was not observed between the patients and control subjects in the genotype distributions and allele frequencies. P300 amplitude in schizophrenia patients was significantly lower than that of controls. The P300 latency in schizophrenia patients was also significantly longer than that of controls. The P300 latency of Met homozygotes was significantly shorter than that of Val/Met and of Val/Val carriers at Cz and Pz. The latency of Val/Met carriers was significantly shorter than that of Val/Val carriers at Pz. The results did not suggest an association between the polymorphism in the COMT gene and susceptibility to schizophrenia in the Chinese Han population. However, the COMT Val158Met polymorphism might be a susceptibility variant for P300 abnormality in Chinese Han schizophrenia.