Many types of active superconducting devices have been proposed over the years. Of these, there are a few transistor-like devices that make use of semiconductor layers in such a way that the semiconductor is an intrinsic part of the device, not merely a tunnel barrier or a substrate. This paper presents an overview of such superconductor-semiconductor hybrid devices, including past and present work and future prospects. Physics of device operation, I-V characteristics, modelling considerations, potential performance, possible uses and comparisons with conventional devices are described. In particular, the potential improvements that may be obtained by using high Tc superconductors in such devices are discussed. © 1990.