Novel amphiphilic diblock copolymers from a combination of hydrophobic-functional poly(lactides) (PLAs) with hydrophilic-functional PLAs or poly(malic acid), respectively, toward fully biodegradable materials for medical applications, such as micellar drug delivery systems, are reported for the first time. The presented PLA-based polymeric micelles are characterized by their small size below 100 nm, low critical micellar concentrations, good in vitro stabilities at room and body temperature, and efficient incorporation capability of hydrophobic compounds, particularly with regard to potential drug substances. Moreover, the advantage of being totally degradable with different rates at different pH values, as investigated in medical cancer treatment, is demonstrated. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3244-3254, 2010