The use of polymer-drug conjugates for the delivery of drugs to specific sites of disease within the body has shown much clinical promise. It has become clear that the conformation that these conjugates adopt can significantly affect characteristics important to therapeutic performance. Using the clinically relevant polymer HPMA, we are investigating the effect that the degree of model drug loading and structure has on conjugate conformation. By systematically altering the 'drug' chemistry we have shown that the conjugate can change from an extended coil to a rod-like morphology. Our results suggest a balance between drug volume and hydrophobicity which may determine the shape of the conjugate. To probe this balance of steric/hydrophobic interactions we propose an extension of this study onto conjugates containing drug models of similar physical size but differing hydrophobicity.