Background: The balance between collagenolysis and its inhibition is critical during extracellular matrix remodeling in head and neck squamous cell carcinoma (HNSCC). An imbalance between matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) plays a critical role in the development of tumor cell invasion and metastasis. The purpose of the study was to determine MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios in the sera of patients with HNSCC in relation to clinicopathological parameters. Methods: Serum samples from seventy patients with HNSCC were measured by ELISA, before and 2 days after surgery. Forty healthy volunteers were selected as controls. Results: Preoperative MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios were significantly higher in HNSCC patients than in the control group (p < 0.001 and p= 0.002, respectively). Changes in MMP-9 concentration and MMP-9/TIMP-1 ratio after surgery had a negative correlation with lymph node involvement (r=-0.35, p= 0.021 and r=-0.37, p= 0.013), while changes in TIMP-1 had a positive one (r= 0.45, p= 0.006). Histological grade was positively correlated with the changes in circulating TIMP-2 level (r= 0.39, p= 0.021). No significant correlation was discovered between MMP-2/TIMP-2 ratio and tumor grade or any clinicopathological variables. Conclusions: Our results suggest that an imbalance between MMP-9 and TIMP-1 could play an important role in metastatic spread via lymphatic pathways of HNSCC cells. MMP-9/TIMP-1 ratio and, in particular, MMP-9, TIMP-1, TIMP-2, may represent suitable biomarkers for early diagnosis and detection of disease progression and dissemination in HNSCC patients.