Primary gastrointestinal melanomas, part of the mucosal melanoma group, are uncommon. They constitute about five percent of all melanomas and most of them are located in the rectum (3 percent of all melanomas). The prognosis is poor, overall 5-year survival in rectal melanoma is 10-20 percent. We present three of our cases. The first case - a 68-year-old male patient - was operated on for histologically proved rectal melanoma. Three years after radical excision and oncological treatment a metastasis of the primary tumor was diagnosed in the stomach. Total gastrectomy was performed, followed by oncological treatment. In the second case of a 59-year-old male patient an appendectomy was performed for symptoms of appendicitis. The histopathological examination revealed melanoma of the appendix. Further investigations revealed the primary tumor in the stomach and metastases in the lungs as well. The third case - an 82-year-old female patient - was investigated for frequent defecations, mucus in stool and fecal incontinence. Primary melanoma was proved in the lower third of the rectum with multiple hepatic metastases. These three cases in our practice are remarkable for the rarity of the disease, and in two cases the presence of both the primary tumor and the metastasis were located in the gastrointestinal tract.