Metal Semiconductor Field Effect Transistor (MESFET) is the most widely used active element of today’s microwave industry. After development of the MESFET technology, the microwave industry gained a high acceleration, especially in the telecommunication field. In this study, GaAs MESFETs with various dimesions and geometries were fabricated. Characterization and parameter extraction of these devices were performed, by means of low and high frequency measurements. The low cutoff frequency of the MESFETs produced were attributed to the non-optimized gate recess etch.