Involvement of Kaposi's sarcoma in the gastrointestinal tract is common in AIDS patients and can also occur in non-AIDS patients. However, the disease is usually asymptomatic and, due to tumor growth primarily in the submucosa, biopsy diagnosis is possible in less than 25%. In the present study, we describe two cases of Kaposi's sarcoma that were first diagnosed in the gastrointestinal tract of a 74-year-old patient who presented to the clinic with nausea and vomiting. On esophagogastroduodenoscopy, a lesion 0.7 cm in size was found. Histology revealed a Kaposi's sarcoma of the stomach with existing HHV8 infection, and there were negative tests for HIV. The second case is a 39-year-old patient with multiple lesions in the stomach and in the small and large intestine. The histology verified multiple Kaposi's sarcomas that were HHV 8-positive. Afterwards, the diagnosis of an HIV infection was made. Primary diagnosis of Kaposi's sarcoma of the gastrointestinal tract in HIV-negative patients is certainly rare and more frequently made in HIV patients. Nevertheless, Kaposi's sarcoma must always be considered in lesions of the gastrointestinal tract or in gastrointestinal bleeding and should lead to further elucidation of the causes.