In situ dynamic experiments in the TEM provide a powerful and unique method of investigating materials, when they are subjected to different environments or treatments. Study of plastic deformation mechanisms of free standing thin metallic films have evoked strong research interest in recent years. In the past, free standing thin metallic films have been tested in tension, where the tensile properties were measured and compared with those of bulk samples. Certain other studies dealt with metallic films attached to the substrate, where the deformation was introduced by thermal cycling or mechanical straining. The deformaion of bulk nanocrystalline samples has also been extensively studied recently. However, few publications have documented in situ straining of free standing metallic films with ultrafine grain size. In this study, an in situ straining stage was employed in the TEM to deform a free standing thin nickel film with grain sizes in submicron and nanocrystalline range, and the goal was to observe the microstructural response to deformation.