The isomerization of silylallene to seven of its isomers has been studied using ab initio molecular orbital theory. The energetics were obtained using quadratically convergent configuration interaction (QCISD(T)) with the 6-311G(d,p) basis set, at geometries optimized by second-order perturbation theory (MP2) with the 6-31G(d) basis set. Test calculations using multiconfiguration wave functions show that the configurational mixing is small; therefore, the single-configuration-based methods are reliable. In comparison to the isomerization of the parent allene, the silyl group was found to migrate more easily than the hydrogen. In particular, the 1,3-migration that converts silylallene to silylpropyne has barriers of 55.8 and 52.9 kcal mol-1 for the forward and backward reactions, respectively. These are roughly half of the 1,3-hydrogen migration barrier in allene.