For large movable parts in the microelectromechanical systems, etch holes are needed to facilitate the releasing process. These etch holes obviously weaken the structure and affect its mechanical properties. New techniques and structures have been developed to measure the mechanical properties of very thin microelectromechanical systems (MEMS) materials. A dog-bone shaped tensile specimen is imposed with a uniaxial stress field and strain is directly measured on the specimen with the interferometric strain/displacement gage. This testing approach has been used to study the effect of etch holes on the mechanical properties of polysilicon thin film. The material is phosphorus doped, low pressure chemical vapor deposited polysilicon deposited at MCNC the multi-user MEMS processes. The specimen is 3.5 mu m thick and 0.6 mm wide at its narrowest point. The etch holes are about 5 mu m in diameter and 30 mu m apart. Compared with the mechanical properties of the specimens without etch holes, the tensile strength has dropped by 50% and the Young’s modulus decreases only about 18% due to the existence of the etch holes. Finite element modeling is applied to the specimens with etch holes and in agreement with the test results.