© 2014 Elsevier B.V. All rights reserved. This review summarizes the reported MEMS resonators integrated monolithically in CMOS technology and their main applications as oscillator circuits in timing applications and in sensory systems. An overview of the CMOS-MEMS resonators acting as filters for signal processing is also included. Special emphasis will be given to the different technological fabrication approaches and their performance, providing specific figures of merit for their comparison as stand-alone resonator as well as oscillator and filter. This review contributes to establish the state-of-the art on CMOS-MEMS resonators.