The incorporation and final containment of spent ion-exchange resins into poly(methyl methacrylate) (PMMA) was investigated in the present study. Test blocks of PMMA with 50% incorporated inactive resin were subjected to radiation doses of 105–107 rad at a dose rate of 50 rad/s. The high radiation doses impaired the mechanical properties of the final products. Both compressive strength and hardness decreased with increasing the particle size of the ion-exchange resin. DTA diagrams showed the thermal instability of the final solidification product at about 400°C. Leaching experiments on incorporated blocks of active resins labelled with Cs-137 and Ce-144 showed that cesium activity was more easily released in leachant solutions than was cerium activity. Cumulative leaching rates for both Cs and Ce were lower in deionized water than in undergroud water. The mechanical, thermal, and leaching data obtained illustrate the suitability of PMMA for immobilization of spent ion-exchange resins with low specific activity.