A six years old boy with Mixed Connective Tissue Disease is presented. Initial manifestations were Coombs positive hemolytic anemia, thrombocytopenia, Arthritis, liver and spleen enlargment.Search for antibodies to extiactable nuclear antigens (ENA) was positive for the ribonuclcase sensitive component (anti-RNP).This syndrome improved under corticosteroid therapy.To our knowledge this is the first report of such onset of MCTD in children.Clinical symptoms, laboratory manifestations and treatment of MCTD in children arc analized.