Filters play important roles in many RF/microwave applications. They are used to separate or combine different frequencies. The electromagnetic spectrum is limited and has to be shared; filters are used to select or confine the RF/microwave signals within assigned spectral limits. A wide variety of microwave filter design techniques are available in different technologies, using different basic microwave structures and topologies such as Insertion loss or Richard method. In any case, conventional microwave filters (obtained by exact synthesis or directly by the Insertion loss method), will be implemented by cascading suitable microwave structures and will include sharp discontinuities at the connection junctions. These sharp discontinuities can be troublesome. In this research, a technique to synthesize microwave filters by inverse scattering, assuming single mode operation, is proposed. This synthesis technique is very flexible, and is valid for causal, passive, and stable frequency responses. The Coupled-mode theory is used to model microwave propagation along the filter, and therefore, the synthesis technique is applicable to filters implemented in a wide range of technologies, such as planar and nonplanar transmission lines, and many waveguides. The synthesis method is exact for all the frequency range of interest, preventing the degradation of the frequency response. The resulting synthesized filter is, in general, a nonuniform transmission line or waveguide that features a continuously varying smooth profile, avoiding the presence of sharp discontinuities and their detrimental effects. Keywords:Microwave filter , Coupled-mode theory, Inverse scattering, Coupling coefficient, Frequency response