In this talk I will speak about the relevance of precise predictions for the LHC physics, focusing on the role of electroweak corrections. I will discuss the automation of the calculation of NLO corrections of both QCD and electroweak origin in MadGraph5_aMC@NLO and I will present phenomenological results for processes involving the top quark and/or the Higgs boson. In the last part I will also discuss how precise measurements of single-Higgs production processes at the LHC can be exploited for setting limits on the trlilinear Higgs self coupling; these processes are indeed sensitive to the Higgs self coupling via electroweak corrections.