Abstract: Objective To investigate the polymorphism of cholecystokinin（CCK） gene -45C/T of schizophrenia and its application in forensic medicine. Methods Bidirectional allele specific PCR was used to detect CCK gene -45C/T polymorphisms in 207 schizophrenic patients （case group） and 202 healthy individuals （control group） of the Han population in northern China. The χ2 test was used to identify Hardy-Weinberg equilibrium of the genotype distribution in control group. The differences of genotype and allele frequencies distributions were compared between two groups. Results Distributions of the genotype frequencies satisfied the law of Hardy-Weinberg equilibrium in control group. The differences between genotypic frequencies and allele frequencies were not statistical significance in case group and control groups（P＞0.05）. Gender-stratified analysis showed that frequency of allele T in female case group was statistically higher than that in female control group（P=0.044）. Conclusion CCK gene -45C/T locus T allele may be positively associated with schizophrenia in female population and useful in schizophrenia identification.

Key words: forensic genetics, forensic psychiatry, polymorphism, genetic, schizophrenia, cholecystokinin