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A new approach to aromaticity of conjugated hydrocarbons is described. It is based on the concept of conjugated circuits, which has been recently recognized as an essential structural element for characterization of conjugated systems (Chem. Phys. Lett., 38, 68 (1976)). Kekulé structures of a conjugated hydrocarbon are examined and circuits with an alternation of CC double and single bonds enumerated. Systems having only (4 + 2) conjugated circuits are defined as aromatic. Systems having only 4n conjugated circuits are considered antiaromatic, i.e., destabilized by the delocalization of ir electrons. Finally, systems having both (An + 2) and An conjugated circuits are classified as intermediate, showing partial aromatic nature. The approach represents a logical generalization of the famous Hiickel (An + 2) rule, valid rigorously only for monocyclic structures, to polycyclic systems. A brief comparison with several alternative schemes is given and their limitations illustrated.