Primary gastric melanoma is an exceptional tumour with less than 20 cases described in the literature, as its origin is not entirely clear as the presence of melanocytes in the stomach has not been demonstrated. Symptomatology is non-specific, which prevents its early detection, and it is diagnosed in late stages. We present the case of a patient who was admitted to our hospital for vomiting in coffee grounds with analytical and haemodynamic repercussions. Urgent gastroscopy revealed a gastric lesion suspicious for malignancy, which was histologically confirmed as gastric melanoma. The therapeutic approach to these tumours is complex and they have a very poor prognosis.