The present invention provides a glycopegylated G-CSF that is therapeutically active and which has pharmacokinetic parameters and properties that are improved relative to an identical, or closely analogous, G-CSF peptide that is not glycopegylated. Furthermore, the invention provides methods for mobilizing hematopoiesis in a subject, particularly a subject who has received or will receive radiation or chemotherapy treatment. The methods and compositions of the invention can further be used to prevent, alleviate and treat the myelosuppressive effects such therapies.