  We study scattering of minimally coupled massless scalar fields by
non-extremal spherically symmetric black holes in d dimensions with
string-theoretical alpha' corrections. We then obtain a formula for the low
frequency absorption cross section for every black hole of this kind, which we
apply to known black hole solutions. We compare the alpha' corrections for the
absorption cross section with those for the black hole entropy, obtained
through Wald's formula, in each case concluding that these corrections are
different. We find a general covariant formula for the absorption cross section
including alpha' corrections, in terms of the horizon area and temperature.
