Tropomodulin1 (TMOD1), which regulates the length and depolymerization of actin filaments by binding to the pointed end of the actin filament, has been reported to be a powerful diagnostic marker for ALK-negative anaplastic large-cell lymphoma; however, little is known about the relevance of TMOD1 in the behavior of oral squamous cell carcinoma (OSCC). We evaluated TMOD1 expression in OSCC-derived cell lines and primary OSCC samples (n=200) using quantitative reverse transcriptase-polymerase chain reaction, immunoblotting and semi-quantitative immunohistochemistry. We also analyzed the clinical correlation between TMOD1 expression status and clinical parameters in patients with OSCC and performed a prospective study using 40 primary OSCC samples. TMOD1 expression was upregulated significantly (p<0.05) in OSCC in vitro and in vivo compared with normal counterparts. TMOD1 expression also was correlated significantly (p=0.0199 and p=0.0064, respectively) with regional lymph node metastasis (RLNM) and 5-year survival rates. This prospective study also showed that high TMOD1 expression was seen in 12 (75%) of 16 cases in RLNM-positive patients and 9 (37.5%) of 24 cases in RLNM-negative patients. The current data provide the first evidence that TMOD1 expression is a critical biomarker for RLNM and prognosis of patients with OSCC.