Interest in high-resolution structure investigation using femtosecond X-rays has been zealous, especially with the advent of X-ray free electron lasers (XFELs). The intense and ultra-short X-ray laser pulses pave new routes to explore structures and dynamics of single macromolecules, complex materials in non-equilibrium states, nano-materials, etc. In the last several years, we have developed XFEL single-shot diffraction techniques by expanding the boundary beyond the present space and time limit. In this talk, I will overview recent progress on femtosecond X-ray diffraction. Further, our research effort on ultrafast pump-probe imaging will be discussed. These will provide a perspective for new science opportunity with femtosecond X-ray pulses from XFELs.