Current and future wireless communications systems have to be smart while proposing an acceptable quality of service for given applications and optimized resource management in terms of energy consumption and spectral occupation. Moreover, the demand for nomadic devices is growing, thus requiring light, low profile and miniaturized microwave components which can easily integrate into complex systems. All these requirements can be contradictory for the conventional microwave engineer since for instance, miniaturization is usually achieved with a non-negligible impact on overall performances. Since metamaterials can be tailored to present required electromagnetic properties, it should definitely provide a higher degree of freedom in the design of both radiative and non-radiative components for wireless systems. The potential of metamaterial to improve the performances of microwave devices should also be considered. This chapter is divided in two main parts: the first one deals with metamaterial applications for non-radiative microwave components and the second one describes the potential and applications of metamaterials to microwave antennas.