The oblique derivative problem for the Laplace equation is studied in a planar multiply connected domain. The boundary condition has a form (n + βτ ) · ∇u = g, where n is the unit normal vector, τ is the unit tangential vector and β is a fixed real number. If g is a Hölderian function and the corresponding domain has Ljapunov boundary then the classical problem is studied. If g ∈ Lp on the boundary and the domain has a locally Lipschitz boundary then a solution, which fulfils the boundary condition in the sense of a nontangential limit, is studied. If g is a real measure on the boundary and the domain has bounded cyclic variation then a solution in a sense of distributions is studied. The solution is looked for in a form of a linear combination of a single layer potential and an angular potential.
Mathematics Subject Classification (2000). Primary 35J05; Secondary 31A10.