The geometries, electronic structures, and stabilities of MSi14 clusters (M = Sc-Ni) have been studied by using density functional theory. The results demonstrate that the cage composed of fourteen Si atoms can completely encapsulate a 3d transition-metal atom. The binding forces of MSi14 clusters mainly origin from the electrostatic and orbital interactions. In binding (or embedding) energy calculation, the Wigner-Witmer spin conservation rule is needed in the cases of CrSi14 and MnSi14. Among MSi14 clusters, only CrSi14 shows the highest stability and chemical inertness simultaneously, indicating that only 20-electron rule can be applied to MSi14 species. (C) 2009 Elsevier B.V. All rights reserved.