This paper presents the latest accomplishments in RF MEMS switches, and at the same time, an assessment of their potential applications in defense and commercial systems. It is seen that RF MEMS devices offer spectacular performance at microwave frequencies, but suffer from reliability problems and the potential of relatively high-cost hermetic packaging. Still, this technology offers such tremendous advantages over GaAs and silicon switching devices that, in the author's opinion, it will find many applications in satellite, base-station and defense applications, particularly at high microwave frequencies.