We discuss the local properties of weak solutions to the equation −Δu + b · ∇u = 0. The Dirichlet boundary value problem for this equation is studied as well. The corresponding theory is well-known in the case b ∈ L_n, where n is the dimension of the space. Our main interest is focused on the case b ∈ L₂. In this case the structure assumption div b = 0 turns out to be crucial.