  We consider the problem of coding for quantum channels with side information
that is available ahead of time at the transmitter but not at the receiver. We
find a single-letter expression for the entanglement-assisted quantum capacity
of such channels which closely parallels Gel'fand and Pinsker's solution to the
classical version of the same problem. This theorem can also be used to find a
lower bound on the unassisted quantum capacity of these channels.
