One important challenge of microsystems design is the implementation of miniaturized actuation principles efficient at the micro-scale. Shape memory alloys (SMAs) have early on been considered as a potential solution to this problem as these materials offer attractive properties like a high-power to weight ratio, large deformation and the capability to be processed at the micro-scale. This paper reviews various attempts made to introduce SMAs in microsystems as well as design principles for SMA microactuators. It presents the status of current research and potential developments from a material research perspective.