A limitation to many polymer-based drug delivery systems is the lack of ability to customize a particular polymer composition for tailoring drug release kinetics to specific clinical application. In this study, we investigated the structure-property effects of conjugating various hydrophobic biocompatible side chains to poly(glycerol-co-caprolactone) copolymers with the goal of achieving prolonged and controlled release of a chemotherapeutic agent. The choice of side chain significantly affected the resulting polymer properties including thermal transitions, relative crystallinity (Delta H-f), and hydrophobicity. Drug-loaded films cast from solutions of polymer and 10-hydroxycamptothecin demonstrated prolonged release from four to over seven weeks depending upon side chain structure without initial burst release behavior. Use of the stearic acid-conjugated poly(glycerol-co-caprolactone) films afforded substantial anticancer activity in vitro for at least 50 days when exposed to fresh cultures of A549 human lung cancer cells over 24 h intervals, correlating well with the measured drug release kinetics.