In this paper, we present various combined field integral equation (CFIE) formulations for the analysis of electromagnetic scattering from arbitrarily shaped three dimensional homogeneous dielectric body in the frequency domain. For the CFIE case, we propose eight separate formulations with different combinations of testing functions that result in sixteen different formulations of CFIE by neglecting one of testing terms. One of the objectives of this paper is to illustrate that not all CFIE are valid methodologies in removing defects, which occur at a frequency corresponding to an internal resonance of the structure. Numerical results involving far scattered fields and radar cross section (RCS) are presented for a dielectric sphere to illustrate which formulation works and which do not.