Cancer is the leading cause of death in the Western World and it affects people through different manners. Oral Cancer is one of the eight more frequent cancer types in Brazil and is related to high mortality rates. Protease inhibitors have been described as potent anticarcinogenic agents acting on broad different cancer processes, targeting altered gene expression and proteolytic activity; tumour growth and metastasis in vitro and in vivo systems. Protease inhibitors derived from soybeans have demonstrated chemopreventive and toxic activity on oral premalignant lesions. In the present study the effects of a low molecular mass Bowman-Birk type protease inhibitor isolated from Vigna unguiculata seeds (BTCI) on oral squamous cell carcinoma (OSCC) were analyzed in vitro. OSCC (1x10⁵) cells/well were seeded on 12-well culture plates and incubated overnight for cell attach. Different mM concentrations of BTCI were added to the cell culture and it was incubated for 24 hours at 37^oC in humidified atmosphere containing 5% CO₂. Light microscopy was used to evaluate cell morphology and MTT and trypan blue dye exclusion assays were used to evaluate cell viability. BTCI-treated OSCC cells presented altered morphology and contained several vacuoles. MTT and trypan blue dye exclusion assays showed that BTCI have a significant effect on OSCC cells viability. This study suggests that BTCI could be used as potent anticarcinogenic agent in oral cancer. Nevertheless, further investigations are needed to evaluate the use of BTCI in in vivo systems facing its application as an alternative agent to conventional oral cancer treatments as radiotherapy and surgery.