  We study both spherically symmetric and rotating black holes with dilaton
coupling and discuss the evaporation of these black holes via Hawking's quantum
radiation and their fates. We find that the dilaton coupling constant $\alpha$
drastically affects the emission rates, and therefore the fates of the black
holes. When the charge is conserved, the emission rate from the non-rotating
hole is drastically changed beyond $\alpha = 1$ (a superstring theory) and
diverges in the extreme limit. In the rotating cases, we analyze the slowly
rotating black hole solution with arbitrary $\alpha$ as well as three exact
solutions, the Kerr--Newman ($\alpha = 0$), and Kaluza--Klein ($\alpha =
\sqrt{3}$), and Sen black hole ($\alpha = 1$ and with axion field). Beyond the
same critical value of $\alpha \sim 1$, the emission rate becomes very large
near the maximally charged limit, while for $\alpha<1$ it remains finite. The
black hole with $\alpha > 1$ may evolve into a naked singularity due to its
large emission rate. We also consider the effects of a discharge process by
investigating superradiance for the non-rotating dilatonic black hole.
