Dense hydrophilic composite membranes for ultrafiltration were prepared from an asymmetric porous PVDF support coated with a thin (< 1 mu m) layer of polyether-block-polyamide copolymer. Membranes with a molecular weight cut-off between 800 and 4500 g/mol and water permeability between 2.3 and 9.4 1 h(-1) m(-2) bar(-1) were obtained. The dry membrane surface was characterized as a dense non-porous layer when observed by scanning electron microscopy. When compared to other commercial membranes and to the non-coated porous PVDF support in the ultrafiltration of oil-water waste, the performance of the composite membranes was comparable to the Amicon YM30 cellulose membrane with lower susceptibility to fouling.