Objective To study the relationship between single nucleotide polymorphisms of MMP1 gene (-1607) and cyclosporine-induced gingival overgrowth ( CsA-GO ) . Methods Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) were used to detect 42 cases of cyclosporine-induced gingival hyperplasia patients and 118 normal controls. MMP1 (-1607) 1G/2G gene polymorphism type were detected and analysised;Logistic regres-sion model was used to calculate the different genotypes and the risk of cyclosporine-induced gingival hyperplasia re-lationship. Results Cyclosporine-induced MMP1 (-1607) 3 genotype frequency distribution of gingival hyperplasiacase group had no significant difference (P=0.37) with the control group. Patients who carry MMP1 (-1607) 2G genotype occurred cyclosporine-induced gingival hyperplasia have 1.37 times risk than 1G genotype (95%CI=0.81-2.36, P=0.24), and 1G genotype and cyclosporine-inducedgingival hyperplasiaun related torisk. Conclusion MMP1 gene promoter region (-1607) 1G/2G single nucleotide polymorphism of cyclosporine -induced gingival hyperplasia may not a genetic susceptibility factor, patients who carry 2G genotype has an increased risk of CsA-GO.