Diseases of the skin and the gastrointestinal tract may occur together. It is important to examine the skin of everyone showing a gastrointestinal problem. Gastrointestinal signs and symptoms in dermatologic diseases may occur with dysphagia, abdominal pain, gastrointestinal bleeding and diarrhea with or without malabsorption. In general the cause is found in a genetic disorder, or it is infectious, drug-induced, inflammatory or related to a malignant disorder. Polyposis are hamartomatous tumors or result as an inflammatory reaction. All these syndromes may present with cutaneous lesions. As malignant degeneration of polyps often develops, the early diagnosis and preventive treatment is crucial. Inflammatory bowel disease is often associated with skin complications such as pyoderma gangrenosum and erythema nodosum. Malignant disorders in the gut may metastasize into the skin or may produce rather typical paraneoplastic changes.