The conversion of treated radioactive wastes by solidification to obtain stable forms is an important step in waste management because in this way the potential for radioactivity release to the environment during storage, transportation and disposal can be minimized. This report reviews current practices in the immobilization of low and intermediate level radioactive wastes with polymers as well as new and promising research and development in this field. Some background information on the properties of polymers is given. Contents: 1. Introduction; 2. Characteristics and sources of low and intermediate level radioactive wastes; 3. Characterization of polymers; 4. Pre-treatment of wastes before immobilization; 5. Immobilization processes; 6. Conclusions.