A chemically modified human Growth Hormone (rhGH)prepared by attaching a transient linkerwhich comprises a polyethyleneglycol. The chemically modified proteinmay have a much longer lastingrhGH activity than that of the unmodifiedrhGH, enabling reduced doseand scheduling opportunities and themodified rhGH may not cause lipoatrophy.Also includes methods of usefor the treatment and/or prevention ofdiseases or disorders in which use ofgrowth hormone is beneficial.