In this study, different Ge IR optical windows are produced and their electromagnetic interference (EMI) shielding performances are investigated. Three Ge single crystals with different doping concentrations are grown by the Czochralski (CZ) technique. Optical windows are obtained after the slicing, lapping, and polishing processes are examined. Formation of (111)-oriented single crystal is observed from the X-ray diffraction (XRD) pattern. In addition, IR transmission of the crystals is measured around 45% in the range of 2-12 mu m using Fourier transform infrared spectrometer (FTIR) spectrometer. EMI shielding effectiveness (SE) of the windows is determined in a flanged coaxial SE tester developed for outer diameter as 1 inch. SE results are evaluated by taking into account both resistivity, thickness of the samples and limitations of measurement fixture.