Polymer microelectromechanical system (MEMS) devices are promising for biological applications such as development of biosensors and biomechanical devices. In order to develop polymer biological MEMS (BioMEMS), polymer microfabrication techniques are required, and the nanomechanics studies, including measurement of the nanomechanical properties of the polymer materials, must be carried out. This article presents the development of soft lithography based polymer BioMEMS microfabrication techniques and systematic studies on the nanomechanical characterization of the polymer thin films and beams. Poly (methylmethacrylate) (PMMA) and poly (propyl methacrylate) (PPMA) are used to make the polymer beams for MEMS integration. The hardness, elastic modulus and creep behavior of PMMA and PPMA thin films and microstructures were measured using continuous stiffness measurement nanoindentation technique, and the scratch resistance of the polymer thin films was measured using a nanoscratch technique. The elastic moduli of the polymer beams were also obtained from bending tests performed by nanoindentation. To simulate the working environment of the polymer BioMEMS, the beams were also soaked in de-ionized water or heated up to human body temperature, and the nanomechanical properties were measured. (c) 2005 American Vacuum Society.