This paper reports a case of sudden bilateral deafness as the first symptom of gastric cancer, an extremely rare and atypical clinical situation. Because common signs of stomach cancer were absent, the patient was first evaluated in the Department of Otolaryngology, University Hospital Center, Zagreb. Only after expanded diagnostic evaluation and rapid progression of the disease in such a case is a malignant tumor suspected. Treatment is mostly ineffective. The unusual presentation of the disease and the rapid course may indicate a hereditary predisposition. Inactivation of tumor suppressor gene DFNA5 was found in 50% of gastric cancers, but of a non-metastasized phenotype. Inactivated DFNA5, otherwise described in hereditary bilateral deafness, perhaps favors the development of deafness in patients with gastric cancer. Our patient had a positive multiple viral antibody titer in serum, inactivated DFNA5 in both gastric cancer tissues and cerebellar metastases, and a metastatic form of the disease. If sudden deafness occurs in elderly patients, the possibility of malignant tumor should be taken into consideration. The link between gastric cancer and the DFNA5 gene is unclear and requires further research.