Erythropoietin glycoprotein products are disclosed which have the in vivo biological activity of causing bone marrow cells to increase production of reticulocytes and red blood cells. The present conjugates have an increased circulating half-life and plasma residence time, decreased clearance, and increased clinical activity in vivo. In addition, compared with conventional PEG-EPO conjugates, the conjugates of this invention have superior clinical properties. The present invention also includes a method for the treatment of anemia in a human employing the novel erythropoietin glycoprotein products as well as a method for preparing the erythropoietin glycoprotein products.
