Objective:To explore the significance of gene mutation of methylenetetrahydrofolate reductase (MTHFR) C677T in the development of acute mesenteric venous thrombosis(AMVT). :Methods :Sixtythree cases of AMVT (AMVT group) and 128 healthy controls (control group) were recruited in the study. The concentrations of plasma Hcy and folic acid were respectively measured by reverse phase high performance liquid chromatography and radioimmunity method. The polymorphism of MTHFR C677T was detected by PCR-restriction fragment length polymorphism (PCR-RFLP). :Results:The plasma Hcy level of the AMVT patients was (23.5±8.8) μmol/L,Which differed significantly from that of the controls,Which was (12.7±6.9) μmol/L (P<0.01). There was obvious negative correlation between the plasma Hcy and folic acid levels (AMVT: r=-0.42, P<0.01, control: r=-0.39, P<0.01). The prevalence of TT genotypes of MTHFR (C677T) between AMVT group and normal control group had significant difference (33.3% vs. 17.2%, χ2=6.31, P<0.05). :Conclusions:The higher plasma Hcy level might be a risk factor in the onset of AMVT. The homozygote of MTHFR C677T (TT) may be an important risk factor of AMVT.