  In the article by M. G. Mustafa published in Phys. Rev. C {\bf 72}, 014905
(2005) the author has estimated the total energy loss of a charm quark and
quenching of hadron spectra due to the collisional energy loss of energetic
partons in an expanding quark-gluon plasma employing Fokker-Planck equation. We
wish to point out through this Comment that some of conceptual and numerical
results of the said paper are unreliable. For the sake of clarity our
discussion will focus on the massless case (although a few remarks on the
$m\neq 0$ case are also made).
