Molecular imprinting technique allows the recognition at molecular level of a wide range of suitable templates. General procedure requires the synthesis of high cross linked polymers in the presence of the template molecule. By removing this latter by means of prolonged washing with suitable solvent, leads to the production of complementary nanocavities which show molecular recognition. Their use in chromatography and solid phase extraction was already achieved. More recently, the formation of molecular imprinted membranes by means of the phase inversion technique extended the separation properties of the membrane at molecular level.