A new spinning technique for hollow fiber membranes with a densified outer toplayer has been developed in our laboratory. This technique makes use of a new type of spinneret having three concentric orifices. Apart from polymer solution and bore liquid as applied in classical spinnerets a third liquid can be pumped through an outer layer. After a certain contact time with the third liquid the nascent hollow fiber membrane meets the coagulation bath. This spinning technique has been applied to produce hollow fiber ultrafiltration membranes. The presence of poly-vinylpyrrolidone in the polymer solution is shown to be essential to induce a porous toplayer. Membranes having a waterflux of 275 L-m-2-hr-1-bar-1 and BSA retention of 97% have been spun. Although more research has to be done the first results seem to be very promising.