In-plane drift velocities determined by full band Monte Carlo simulations and drift mobility calculations are reported for electrons in strained Si grown on Si1-xGex substrates up to x=0.4 at 77 and 300 K. Drift mobilities of 28200 cm(2)/(V s) at 77 K and 2230 cm(2)/(V s) at 300 K are found for x=0.3. Strain enhances the drift velocity significantly only below electric fields of about 50 kV/cm. At 77 K the Gunn effect is predicted to occur above 15 kV/cm. (C) 1997 American Institute of Physics.