Tuberculosis and malignant neoplasms are a global threat, these diseases claim millions of lives and cause tremendous suffering to people worldwide. Tuberculosis can mask cancer and create preconditions for carcinogenesis. The article presents a clinical case of tongue cancer in a patient with pulmonary tuberculosis. Patient B.N., 45 years old, was admitted to the FSBI “Novosibirsk Tuberculosis Research Institute” with complaints of a "sore place" on the tongue, pain in the right half of the tongue, enlargement of the submandibular lymph nodes on the right The tongue hurts for about 1,5 years, but over the last 2 months, condition has worsened. The patient noticed an increase in the size of lesion on the tongue and increased pain, especially during meals (he can eat only after pain relief, for which he takes Nimesulide 4 pills a day). In recent days, he felt also epigastric pain for which he didn’t visit a doctor. Tongue biopsy was performed, and histological analysis revealed cancer. The patient was diagnosed with fibrous-cavernous tuberculosis of the upper lobe of the right lung, infiltration and seeding phase; mycobacterium tuberculosis (+); broad drug resistance (HRSECmKmPasCsOfl); gastric ulcer (0,5 cm), exacerbation stage; chronic erosive gastritis, exacerbation stage; malignant neoplasm of the floor of the mouth on the right T3(4)N1M1. With this diagnosis, the patient was discharged for further treatment by oncologists. Physicians need to have a high alertness for cancer in patients with tuberculosis, especially those in the high-risk group. A minimum of standard diagnostic procedures will allow you to verify the diagnosis timely.