Quantum field theory with an interaction on the boundary

We consider quantum theory of fields ϕ defined on a D dimensional manifold (bulk) with an interaction V (ϕ) concentrated on a d < D dimensional surface (brane). Such a quantum field theory can be less singular than the one in d dimensions with an interaction V (ϕ). It is shown that scaling properties of fields on the brane are different from the ones in the bulk. We discuss as an example fields on de Sitter space.