Objective:To investigate the etiological role of the Val384Asp in hMLH1 gene in familial colorectal cancer. Methods:a 1∶2 matched case-control study was conducted in three of the high gastrointestinal cancer incidence areas in Jiangsu. Subjects included 33 familial colorectal cases,66 sporadic cases and 66 health individual controls. Peripheral white blood cell DNA was obtained from all subjects. hMLH1 gene T1151A was analysed using a PCR-based DHPLC,and the existence of Val384Asp was verified by DNA sequencing. Bioinformatics software was used to analysis the etiological mechanism of Val384Asp. Results:There was no statistical difference in the genotype frequencies of the Val384Asp between the cases and controls(P > 0.05). The significant difference existed between the old patients (onset age≥50)with familial colorectal cancer and the health controls(P < 0.05);Bioinformatics software analysis showed Val384Asp was a conserved variant between species and may impair hMLH1 protein function;the allete transverse of T→A may disrupt pre-mRNA splicing. Conclusion:These findings suggested that the Val384Asp may not be associated with genetic susceptibility to colorectal cancer in the genealogical members of familial colorectal cancer,but have a strong relationship with the morbidity of old patients in this group;and be associated with disrupting of protein function or pre-mRNA splicing.