New biologically active drug polymer derivatives, namely peptides or protein derivatives, are useful medicaments and are represented by the generic formula: RO-(CH2-CH2O)n-(CO)-NH-X-(CO)-NH-Z ,wherein R represents a lower alkyl group, n is an integer comprised between 25 and 250, X when combined with adjacent NH and CO groups represents an amino acid or a dipeptide or tripeptide residue, and Z when combined with the adjacent NH group represents a biologically active peptide or protein or NH or NH2 containing drug residue
