  A general formalism for computing only the rational parts of oneloop QCD
amplitudes is developed. Starting from the Feynman integral representation of
the one-loop amplitude, we use tensor reduction and recursive relations to
compute the rational parts directly. Explicit formulas for the rational parts
are given for all bubble and triangle integrals. Formulas are also given for
box integrals up to two-masshard boxes which are the needed ingredients to
compute up to 6-gluon QCD amplitudes. We use this method to compute explicitly
the rational parts of the 5- and 6-gluon QCD amplitudes in two accompanying
papers.
