Radioimmunoassay (RIA) is a laboratory technique within Nuclear Medicine that generates a great volume of radioactive liquid wastes. Generally, these wastes are temporarily stored in the sanitary centre for partial activity decay and then they are managed by an authorized company. However, sometimes hospitals do not have enough storage capacity for all the RIA wastes. The treatment of these wastes with the aim of volume reduction would solve storage problems and would result in a decrease of later management costs. Membrane processes are being applied more and more often in the nuclear industry for removing radioisotopes and reducing waste volume thanks to some advantages such as effectiveness and less energy consumption. The purpose of this research is to study the feasibility of treating radioactive liquid wastes from RIA by means of membrane techniques. Some experimental tests with ultrafiltracion (UF) and reverse osmosis (RO) membranes were carried out with real RIA wastes. This paper presents membrane performance with regard to radioactivity removal in these experiments. Experimental results prove that UF and RO combination is a suitable way of treating radioactive liquid wastes from RIA.