Ab initio (MP2) and density functional theory (DFT) calculations for six neutral (structures 1–6), six cationic (structures 1 + –6 + ) and six anionic (structures 1 − –6 − ) isomers of B 7 clusters have been performed. With only a few exceptions, all isomers are genuine minima. The hexagon capped by an atom structures (C 2v symmetry) are global minima for B 7 (1) and B 7 − (1 − ) and the hexagonal pyramid structure (C 6v symmetry) is the most stable B 7 + (1 + ). The aromatic natures of 1 and 1 + , as well as the anti-aromatic character of 1 − are also discussed.