Solvability and regularity of the solution of the Dirichlet problem for the Prandtl equationWe introduce the scale of spaces H s (−1, 1) in terms of the special integral transformation on the interval (−1, 1). We obtain theorem about existence and uniqueness of the solution in the classes H s (−1, 1) with 0 s 1. In particular, for s = 1 the result is as follows: if r 1/2 f ∈ L2, then r −1/2 u, r 1/2 u ′ ∈ L2, where r(x) = 1 − x 2 .