Abstract: Integral gradient, skinned, submicroscopically porous, anisotropic, hydrophilic, asymmetric polyamide membranes comprising:(a) a first porous polyamide zone obtained from a polyamide solution formulated to give coagulated film with pores of a given size,(b) a fabric support imbedded in the first porous polyamide layer, and(c) a second porous polyamide zone having a skinned outer surface, obtained from a polyamide solution having the same constituents as the solution used to form the first porous polyamide zone but solution post-treated to give pores substantially smaller than those in the first porous polyamide zone, as well as a process for producing such membranes, are disclosed.