GaAs m.e.s.f.e.t.s with gate dimensions of 1.5 μm × 300 μm were fabricated in the epitaxial layers grown by organometallic chemical vapour deposition (o.m.c.v.d.) technique. The average saturation velocity in the channel was deduced to be 1.3 × 107 cm/s and is equal to that of epitaxial layers grown by AsCl3 chemical vapour deposition (c.v.d.). The velocity degraded region was confined to within about 350 Å of the interface. A gain of 10 dB and a noise figure of 3 dB with an associated gain of 5.5 dB at 8 GHz were measured.