We report a rare case of gastric collision tumour composed of poorly differentiated adenocarcinoma and neuroendocrine carcinoma in a 56-year-old Caucasian male. The tumour was located in the gastric body and, to our knowledge, it is the tenth case described in the literature and the first in Poland. The adenocarcinoma component constituted 20% of the lesion and was in a more advanced stage than the neuroendocrine component. Additionally, the adenocarcinoma was the only one to metastasize to regional lymph nodes and the liver. The controversies regarding nomenclature of such lesions are discussed and a review of the literature is presented.