  We show how the MHV diagram description of Yang-Mills theories can be used to
study non-supersymmetric loop amplitudes. In particular, we derive a compact
expression for the cut-constructible part of the general one-loop MHV
multi-gluon scattering amplitude in pure Yang-Mills theory. We show that in
special cases this expression reduces to known amplitudes - the amplitude with
adjacent negative-helicity gluons, and the five gluon non-adjacent amplitude.
Finally, we briefly discuss the twistor space interpretation of our result.
