Microstrip structures have been widely used in microwave integrated circuits and in printed antenna systems. In this study the effects of uniaxially anisotropic type superstrate shielding on the resonant characteristics of a circular microstrip patch are investigated via spectral domain analysis. In the study, Green's functions are determined from spectral domain immitance approach. The results obtained indicate that resonant frequency and bandwidth of a circular microstrip patch is considerably affected from the uniaxially anisotropic superstrate. These results point out that in shielding applications, uniaxial anisotropy must be taken into account in order to make the superstrate as the useful part of the structure.