AbstractSoluble synthetic polymers will only be useful as drug carriers, if methods can be devised for targeting them to specific cell types. Two approaches are currently being investigated. Firstly, the incorporation of specific residues such as galactosamine into N‐(2‐hydroxypropyl) methacrylamide copolymers has been shown to enhance greatly pinocytic capture by liver cells. Secondly, antibodies have been evaluated as a more universal address system. Binding rat IgG to N‐(2‐hydroxypropyl) methacrylamide copolymers increased their rate of uptake by rat visceral yolk sacs culturedin vitroand simultaneously enhanced their rate of exo