Objective To probe the association between possible single nucleotide polymorphism (SNP) in the FGB promoter region and idiopathic deep venous thrombosis.Methods A prospective analysis was performed in both IDVT group and control group (120 cases each) followed by a duplex examination using gene sequencing technique and restriction fragment length polymorphism (RFLP) in the promoter region of fibrinogen gene β.Possible SNPs in this region were detected arranged before HardyWeinberg equilibrium test and Linkage disequilibrium (LD) analyses.Ultimately,we compared the genotype frequencies between the two groups and undertook a multiple Logistic regression.Results Six kinds of SNPs were determined in the promoter region of β-fibrinogen gene:-148C/T,-249C/T,-455G/A,-854G/A,-993C/T and-1420G/A.A stronger linkage disequilibrium was confirmed between-993C/T and -455G/A (r2 =0.699) ;-993C/T and-148C/T (r2 =0.509) ;-455G/A and-148C/T (r2 =0.556).Statistical differences of genotype frequencies between two groups were observed in-148C/T,-249C/T,-455G/A and-1420G/A polymorphisms (all P ＜ 0.05).Conclusions The risk of IDVT was 4.579 times higher with every 1 g/L increase of fibrinogen concentration.Allele-148T,-455G and-1420A are IDVT risk factors.-993C/T may indirectly affect IDVT through linkage disequilibrium with-455G/A and-148C/T.