  We prove that any 3-dimensional singular hyperbolic attractor admits for any
H\"older continuous potential $V$ at most one equilibrium state for $V$ among
regular measures. We give a condition on $V$ which ensures that no singularity
can be an equilibrium state. Thus, for these $V$'s, there exists a unique
equilibrium state and it is a regular measure. Applying this for $V\equiv 0$,
we show that any 3-dimensional singular hyperbolic attractor admits a unique
measure of maximal entropy.
