First-principles calculations were used for investigating the electronic structure of icosahedral quantum dots (IQD) for tetravalent semiconductors. The density functional formalism was used within the local density approximation (LDA) and ultrasoft pseudopotentials. The electronic structure of Si was considered for investigations and it was found that pristine IQD were more stable than bulklike ones. The stability of hydrogenated IQD which were more atomiclike with larger level spacing and fivefold orbital degeneracy was also confirmed.