  The AdS_3/CFT_2 correspondence is checked beyond the supergravity
approximation by comparing correlation functions. To this end we calculate 2-
and 3-point functions on the sphere of certain chiral primary operators for
strings on AdS_3 x S^3 x T^4. These results are then compared with the
corresponding amplitudes in the dual 2-dimensional conformal field theory. In
the limit of small string coupling, where the sphere diagrams dominate the
string perturbation series, beautiful agreement is found.
