  We investigate the trace anomaly of a chiral fermion in dimensional
regularization, considering in detail the simplest case of coupling to an
abelian gauge field. We apply the Breitenlohner-Maison/'t Hooft-Veltman
prescription for dealing with the chiral matrix $\gamma^5$ and verify that no
parity-odd term arises in the trace anomaly. The issue treated here is
analogous to that of a chiral fermion in curved spacetime, discussed in recent
literature. The advantage of having a simplified background minimizes the
amount of algebraic calculations and allows pinpointing better the subtle
points carried by dimensional regularization.
