SummaryMastocytosis is a chronic disease accompanied by specific infiltration of mast cells into the skin and other tissues.In 90 % of cases only the skin is involved. In systemic mastocytosis there is an abnormal proliferation of mast cells in various organs including the gastrointestinal tract and liver. Release of various mediators and infiltrative growth of the mast cells lead to the symptoms of the disease. Therefore, many patients present with abdominal symptoms. The clinical manifestations are reviewed with special focus on the gastrointestinal and hepatic involvement. The prognosis of the disease is variable but most often benign. The treatment is based on H1 and H2-blockers and disodium cromoglycate.