In this study the dry-wet spinning technique is used for the preparation of hollow fiber membranes. In the polymer solution a blend of two polymers, poly(ether sulfone) and poly(vinyl pyrrolidone), is used. The morphology of the membranes obtained is related to rheological characteristics and phase behavior of the polymer solution during spinning. The outer surface pore structure is mainly dependent on the conditions in the airgap. The typical performance of the membranes lies in the ultrafiltration region.