I will present predictions for the SM-Higgs-pair production channels at the LHC. Results, shown in arXiv:1401.7340, are at the NLO accuracy in QCD, and matched to parton showers by means of the MC@NLO method; hence, they are fully differential. I will show that for all channels in general, and for gluon-gluon fusion which is the dominant production channel, in particular, NLO corrections reduce the theoretical uncertainties, and are needed to provide reliable predictions for total rates as well as for distributions. I will also briefly present results for Higgs pair production in the 2HDM, for specific benchmark points.