In the province of Västerbotten, Northern Sweden, we have observed a blood disease formerly unknown in Europe. It is characterized by: 1. A non-hemolytic normochromic anemia with a low or normal reticulocyte count and without indications of reduced or increased activity of either granulocytopoiesis or thrombocytopoiesis. 2. A characteristic bone marrow picture corresponding to the di Guglielmo disorder. 3. An abnormal hemoglobin. 4. A favorable clinical course, but refractory to therapy. 5. An hereditary component.