Abstract: The NBMO of alternant hydrocarbons could be determined by the “star notation” method. The coefficients of the NBMO of odd alternant hydrocarbons are easy to be calculated using the “zero-sum rule” through undetermined coefficient method. Since multiple NBMOs may exist in some even alternant hydrocarbons, more than one algebra number must be employed for the star notation in the determination of the coefficients. A good agreement was observed between the results from “star notation” method and DFT calculations.