The present invention relates to novel conjugates between polypeptide variants of protein C and a non-polypeptide moiety, such as PEG or sugar moieties. In particular, the present invention provides novel protein C conjugates having an increased resistance to inactivation by e.g. human plasma and .alpha..sub.1-antitrypsin. Consequently, such conjugates have an increased in vivo half-life. Preferred examples include protein C conjugates, wherein at least one additional in vivo N-glycosylation site has been introduced. The conjugates of the invention are useful for treating a variety of diseases, including septic shock.