A polymeric drug comprising an inert synthetic polymeric carrier combined through aminoacid or peptide spacers with a bioactive molecule, a targeting moiety, and an optional cross-linkage, comprises:
(a) 5.0 to 99.7 mol % of units derived from N-(2-hydroxypropyl) methacrylamide, (b) 0.2 to 20.0 mol % of units derived from an N-methacryloylated peptide, the peptide groups being bound to a bioactive moiety, (c) 0.1 to 94.8 mol % of units derived from N-methacrylamide, N-methacrylic acid or an N-meth- ecryloylated aminoacid or peptide, to which are bound a determinant capable of interacting with specific receptors on cell surfaces, (d) optionally, 0 to 5 mol % of units derived from an N-methacryloylated peptide, the peptide groups being bound to a linking group which is similarly attached to a similar peptide group attached to another polymer chain, and (e) optionally, as a bioassay label, Q to 2 mol % of units derived from N-methacryloylated tyrosinamide.