In this contribution, it is shown that complementary spiral resonators (CSRs) (ire useful particles for the miniaturization of planar microwave components based on metamaterial concepts. Specifically, we will focus on two different applications: (i) the design of high pass filters based on balanced composite right/left handed microstrip lines and (ii) the design of dual hand impedance inverters, which can be applied to many different devices such as couplers and power dividers, among others. (C) 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2741-2745, 2009: Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24715