Ground-motion Intensity Measures (IM) are parameters that synthetically describe the intensity of ground-motions; with particular reference on their effects on structures. IMs play an important role in performance based seismic design and in ground-motion selection procedures, because they are the link between seismic hazard and seismic demand analysis. Many researchers have proposed IMs and investigated their performances, in particular, in terms of efficiency, sufficiency and scaling robustness. Unfortunately most of these analyses are based on limited case studies that make use of small sets of ground motions. The present paper aims at providing a comprehensive comparison of the efficiency and sufficiency of the most important IMs proposed in the literature. This study makes use of a large dataset of accelerograms (1700 records) and employs cloud-analysis and stepwise regression to investigate their efficiency of sufficiency with reference to various inelastic SDOF and MODF structures