Matrix metalloproteinase (MMP) 9, a key member of multifunctional family of zinc dependent endopeptidases has been found to be upregulated during inflammation and in some cancers. MMPs cleave extracellular matrix (ECM) proteins and play critical roles in cellular apoptosis, angiogenesis, tumor growth and metastasis. Several genetic polymorphisms have been identified that show allele specific effects on MMP9 regulation and are associated with gastric cancer, the fourth most common malignancy in the world. Besides Helicobacter pylori infection, genetic predisposition is another documented risk factor for gastric carcinoma. The single nucleotide polymorphism (SNP) at position -1562C/T of MMP9 results in the modulation for binding of transcription factors to the MMP9 gene promoter and thereby causes differences in protein expression and enzymatic activity. MMP9 transcriptional regulation during gastric cancer development remains poorly known although several studies have demonstrated associations between MMP9 -1562 C/T polymorphism with different diseases. Knowledge on mechanisms of MMP9 upregulation during gastric cancer may provide new paradigm in diagnostics andtherapeutics.