Sarcomatoid carcinoma (SC) is an infrequent variant of squamous cell carcinoma. A 62-year-old male patient with a long smoking and drinking history reported difficulty swallowing due to a rapidly growing mass in the floor of the mouth for 5 weeks. Intraorally, an exophytic mass of 2 cm was observed. After biopsy, histopathologic examination revealed a proliferation of neoplastic cells with epithelial differentiation, organized in nests and islands, as well as fascicles of spindle cells, exhibiting intense cellular pleomorphism and the presence of numerous atypical mitoses. Neoplastic cells with epithelial morphology were positive for anti-AE1/AE3 antibody and the spindle cell component strongly positive for vimentin and alpha-SMA. The anti-Ki67 antibody showed 38% of positivity in the epithelial component and 22% in the spindle cell component. The diagnosis of SC was made. The patient underwent chemotherapy but died after 12 months of treatment. Sarcomatoid carcinoma (SC) is an infrequent variant of squamous cell carcinoma. A 62-year-old male patient with a long smoking and drinking history reported difficulty swallowing due to a rapidly growing mass in the floor of the mouth for 5 weeks. Intraorally, an exophytic mass of 2 cm was observed. After biopsy, histopathologic examination revealed a proliferation of neoplastic cells with epithelial differentiation, organized in nests and islands, as well as fascicles of spindle cells, exhibiting intense cellular pleomorphism and the presence of numerous atypical mitoses. Neoplastic cells with epithelial morphology were positive for anti-AE1/AE3 antibody and the spindle cell component strongly positive for vimentin and alpha-SMA. The anti-Ki67 antibody showed 38% of positivity in the epithelial component and 22% in the spindle cell component. The diagnosis of SC was made. The patient underwent chemotherapy but died after 12 months of treatment.