Nanometer scale features (75–1000 nm) were defined on GaAs/AlGaAs heterostructure surfaces by electron beam patterning. The use of low‐voltage, helium‐ion damage laterally confined the two dimensional electron gas to these patterned areas. Electrical characterization of the conducting channels as well as the ion‐damaged material outside the patterned areas included measurements of the Hall mobility, the carrier concentration and the sheet resistance at various temperatures. The major problem encountered with the nanowires was an increase in the wire sheet resistance over the as‐grown value at 4.2 K. Process‐related factors contributed to this increase, but the most probable cause is boundary scattering at the lateral edges of the nanowires.