Only a few works on fatigue behavior of thin films under tension-tension loading can be found because of some limitations of a testing system. In this study, a fatigue testing system capable of performing load controlled tension-tension fatigue tests even for ductile thin films was developed by using an electrodynamic actuator. With the system, fatigue testing can be performed over a wide range of loading frequency. Besides, a capacitive displacement gauge was developed to measure the monotonic and cyclic deformation of thin films with high resolution during fatigue testing. As the displacement gauge is stable and its response is so fast, the displacement can be measured instantaneously and continuously during fatigue testing of high frequency. (C) 2008 Elsevier Ltd. All rights reserved.