The explanation of GaAs metal-semiconductor field-effect transistor (MESFET) operation often involves the use of simplistic analytical formulas, which set ve to obscure the more subtle physics of device action. We consider here a simple one-dimensional (1-D) model for GaAs MESFET's, which avoids more confusing numerical modeling schemes, Set still facilitates an analysis of the physical functionality of the de,ice. The model takes into account current saturation due to either velocity saturation or channel pinch-off, the modulation of effective gate length, and the series resistance of the regions beyond the gate. The results of the model have been compared to experimental data readily obtained from the literature, and the agreement has been shown to be good.