The structures and relative energies of the bond stretch isomers of tetrasilabicyclo[l.l.O]butane (1), 1,2,3-trisilabicyclo[ l:l.O]butane (2), and 1,3-disilabicyclo[l.l.O]butane (3) are predicted at the GVB/3-21G* level, with the u and u* bridge bond molecular orbitals correlated in the GVB wave function. The transition-state structure and intrinsic reaction coordinate connecting each pair of bond stretch isomers are calculated. Two transition states joining the bond stretch isomers of 3 are located. The more stable isomer in all three molecules is the one with the longer bridge bond.