Several dozen rare-earth containing half-Heusler phases that crystallize in the noncentrosymmetric cubic MgAgAs-type structure have recently been proposed, according to electronic structure calculations, as plausible 3D topological insulators. Representatives of this class of materials host time-reversal-symmetry-protected helical surface states with Dirac fermions that emerge due to nontrivial Z2 topology. Unusual nature of topological insulators makes them an experimental platform for gripping physics such as Majorana fermions and quantum Hall effect, with potential applications in quantum computing.