Microwave dielectric ceramics are irreplaceable components used in devices and systems utilized at microwave frequencies for example mobile and satellite communication systems. In this study the effect of the addition of different amounts of BaZrO3 on the microstructure and microwave dielectric properties of a composition based on  Ba(Zn1/3Nb2/3)O3 (BZN) ceramic, i.e. (0.9-x)Ba([Zn0.6Co0.4]1/3Nb2/3)O3–0.1Ba(Ga1/2Ta1/2)O3–xBaZrO3 where x=0-0.1, has been investigated. Density increased with an increase in BaZrO3 content up to x=0.08 and then decreased. XRD analysis showed the presence of BZN phase together with a small amount of anunknown second phase for ceramics with x=0, 0.02 and 0.04. However, microstructural investigations through optical microscopy showed that ceramics with x=0.06, 0.08 and 0.10 also contained a second phase which could not be detected by X-ray diffraction technique because a small amount of the second phase was present. No super structure peak was observed for ceramics with different BaZrO3 levels. Quality factor for the sample with x=0.08 was 4366 GHz which was very low. The measurement of quality factor for other samples was not also possible due to their low Q values. As mentioned beforeَ showed that all samples contained a second phase; therefore, the low values of quality factor observed for all samples could be attributed to the presence of the second phase.