The discovery of neutrino oscillations suggests the existence of right-handed neutrinos. LHC can probe right-handed heavy neutrino masses inaccessible to previous direct and indirect searches. In particular, models predicting Majorana neutrinos can result in striking experimental signatures of like-sign lepton pairs with two additional high transverse momentum jets. In this talk, we present the results of searches for heavy Majorana neutrinos using the ATLAS and CMS detectors.