Monolithic microwave amplifiers showing gain from 0 to 8 GHz have been fabricated on semi-insulating GaAs. These amplifiers utilized MESFET devices with gate lengths of approximately 0.75 µm and gate widths of 300 µm. The active devices were used to provide both gain and impedance matching. The performance of these amplifiers is promising and indicates that stable, high gain, microminiature gain modules can be made by this 'monolithic microwave integrated circuit' (MMIC) technology.