Malignant melanoma of the stomach is a very rare tumour. In all publications the authors express their suspicion of metastases to the gastric wall which must be carefully excluded. In our case of a 75-year-old man, the diagnosis of a large gastric melanoma (diameter 10 cm) was established by explorative laparotomy. Clinically extensive exploration for a primary tumour of the skin, the anal region, the nose, the eyes was not successful. One month later the patient died. Autopsy revealed brown-black metastases in the liver, the perigastric lymph nodes, the brain, and the cerebellum. Microscopically the stomach tumour was composed of nests and sheets of epithelioid cells with typical solid alveolar pattern. In the tumour cells both argentaffin and argyrophil granules were present. Immunohistochemistry revealed a positive reaction with S100 protein and HMB45 antibodies. Histogenesis of primary melanoma of the stomach and oesophagus is discussed.