The authors present a critical survey of some representative technologies which are candidates for the development of microactuators for microrobots. Since the field of 'microrobotics' is an entirely new one, some concepts and definitions are given first; in particular, a distinction between 'micromachines' and 'microrobots' is proposed. Then, a further classification is proposed between three different types of robots: the 'miniature' robot, the 'microrobot' and the 'nanorobot', and their expected performances and fields of applications are discussed. The need for developing dedicated miniature actuators and microactuators emerges clearly from this discussion, together with the main requirements for this class of 'new' actuators. Finally, some significant examples of implementation of microactuators are illustrated, and the main advantages and limitations of each technology are discussed.