‘‘Ballistic’’ electron transistors are of considerable interest for high‐frequency operation. Regardless of the mechanism of electron injection or collection it is anticipated that device performance will be dominated by base transit dynamics. We address this issue by calculating the scattering rate for hot electrons in selected semiconductor materials holding some common band structure and transport properties. It is shown that the scattering rate is critically dependent on the carrier concentration and that GaAs is not suitable for fabrication of traditional ‘‘ballistic’’ electron transistors. We suggest that semiconductors with small effective electron mass or a two‐dimensional system would be more suitable.