The noise performance of a GaAs FET (series Gat. 1, Plessey, England), operating in the pinchoff mode and in the common-source configuration, is examined neglecting thermal effects due to the velocity saturation. The complete equivalent circuit of the transistor including all extrinsic and package elements is used to obtain the noise figure of the transistor in the frequency region between 0.5 and 4 GHz. All computations of the noise figure are made using the noise model of van der Ziel.