Melanoma accounts for 1-3% of all malignant tumors. In addition to the skin localization, there are other, less common localizations of tumors. This is the primary melanoma of the gastrointestinal tract. However, their primary or secondary nature is often difficult to establish. As regards to the stomach, individual cases of its primary melanoma have been reported in the literature. This paper describes a case of a tumor of the cardioesophageal zone in a male. Epithelioid cell melanoma has been morphopathologically proven. Detailed clinical and laboratory examinations have not revealed the primary focus of another localization. The patient has undergone extended combined gastrectomy with the resection of the lower and mid thoracic esophagus, the esophageal ring of the diaphragm, D3 lymph node dissection with upper para-aortic lymph node dissection, with the formation of loop intrathoracic esophago-enteric anastomosis at the level of the root of the left lung, followed by immunotherapy with an anti-PD-1 blocker. Primary gastric melanoma is an exceptionally rare phenomenon with a limited number of cases that can be described in the literature; therefore, the authors of this article present this case for consideration.