The production rate of the CP-odd Higgs boson in
the Minimal Supersymmetric Standard Model is evaluated through
next-to-leading order in the strong coupling constant. The divergent
integrals are regulated using Dimensional Reduction, with a
straightforward implementation of $\gamma_5$. The well-known Standard
Model result is recovered in this scheme through a cancellation between
the quark and squark contributions as the masses of the supersymmetric
particles tend to infinity.