Abstract: Asymmatric, porous polyamide membranes permeable to fluid flow comprising:(A) a porous skin layer, and(B) adjacent to the skin layer, an integral, porous support layer having at least one region comprising a network of substantially parallel, hollow tube-like structures, each of the tube-like structures being oriented such that the longitudinal dimension of each tube-like structure is essentially perpendicular to the skin layer;whereinthe skin layer is relatively thin and dense compared to the support layer,the pore diameters in the skin layer are relatively small compared to the diameters of the tube-like structures in the support layer,in membrances having support layers with more than one region, the cross-sectional area of the tube-like structures is larger in regions located farther from the skin layer, andthe polyamide is an aliphatic polyamide having a glass transition temperature of less than 200.degree. C., and method of making the same.