We describe an approach to realize quasi-one-dimensional electron gases using an undoped GaAs/AlxGa1-xAs heterostructure. It is demonstrated that with a combination of ion implanted ohmic regions and a narrow top gate, a quasi-one-dimensional electron gas with a very high electron density can be formed. The width of the narrow top gate is varied between 0.4 and 1.0 μm. The wires are characterized by low temperature magnetotransport experiments. The effective wire width is found to be comparable to the gate width. The high mobility of about 95 m2/V s is only 5%–10% less than that obtained in a two-dimensional electron gas of the same material and is maintained at low temperatures. © 1997 American Institute of Physics.