We study the nearest neighbor Ising model with ferromagnetic interactions in the presence of a space dependent magnetic field of type 1/|x|^{\alpha}. We prove that in dimensions d >= 2 for all \beta large enough if \alpha > 1 there is a phase transition while if \alpha < 1 there is a unique DLR state. Jointly with Marzio Cassandro (GSSI, L'Aquila), Errico Presutti (GSSI, L'Aquila) and Leandro Cioletti (Unb, Brazil).