  We comment on the conclusion by Teng et al. [J. Phys. D: Appl. Phys. {\bf
42}, 135111 (2009)] that the Bir-Aronov-Pikus mechanism is more important than
the D'yakonov-Perel' mechanism at high carrier density in intrinsic bulk GaAs.
We point out that the spin relaxation is solely from the D'yakonov-Perel'
mechanism.
