One of the important issues in endohedral fullerene chemistry is the generation of a suitable window for atoms or small molecules to enter into the fullerene cages. In this paper, the structure and stability of fullerenes possessing holes, formed by removing one or more adjacent atoms from the C-60 clusters, are examined via ab initio Hartree-Fock and density functional theory calculations. When vacancies are created in the C-60 cluster, some of the original 5- and 6-member rings are destroyed, resulting in defect structures, containing larger rings (7-, 8-, and 9-member rings) and abutting 5-member rings. It was also found that the ground state is a singlet for the defect C-60 structure with two vacancies and a triplet for the defect structures with one or three vacancies. The vacancies decrease the cluster stability. However, among these defect structures, the two-vacancy defect C-60 with a 7-member ring is the most stable and has a hole with a sufficiently large diameter (3.22 Angstrom) for atoms or small molecules to pass through. Therefore, this fullerene cage could provide an excellent cage for fullerene endohedral complexes and as a storage place for fuels (such as H-2). (C) 2003 American Institute of Physics.