In this study, a hybrid method for fast frequency analysis of E-plane type dielectric loaded metallic rectangular waveguides is introduced. The computational efficiency of mode-matching (MM) method and the flexibility of method of moments (MoM) are integrated. MM based generalized scattering matrix (GSM) method is utilized for computation of scattering parameters and the required GSMs are constructed via MoM. The computational performance and accuracy of the proposed approach are evaluated by comparing with traditional MM and Finite Element Method (FEM) based software High Frequency Structure Simulator (HFSS) for various microwave devices built by dielectric loaded waveguides. The efficiency of the proposed method is also evaluated against arbitrarily shaped structures. (C) 2018 Elsevier GmbH. All rights reserved.