A new, efficient method of moments (MoM) is developed for accurate, full-wave analysis of microstrip components and circuits. The new method is applied for the analysis of a two-gap filter. The new method is found to be as accurate as conventional moment methods, and also significantly faster. It has a good potential for use in the microstrip design of CAD tools. The key to the high efficiency of the new MoM is the use of a set of newly developed closed-form Green's functions, which allow the computation of the MoM matrix elements without any numerical integration when using the RWG function as the basis functions.