Miguel AFP, et al. - Via performing a systematic review, researchers sought to compile and critically appraise available evidence on relationships between immunohistochemical expression of matrix metalloproteinases (MMPs) and the occurrence of lymph node/distant metastasis of oral squamous cell carcinoma (OSCC). From five main electronic and three gray literature databases, 50 records were included in qualitative analysis. The studies suggested a total of 12 MMPs (-1, -2, -3, -7, -8, -9, -10, -11, -13, -25, -26, and MT1-MMP). A positive association of MMP-1, -2, -3, -7, -9, and MT1-MMP with lymph node metastasis was reported in most included studies. This suggests an important role of MMP-1, -2, -3, -7, -9, and MT1-MMP in lymph node metastasis of OSCC.