This study aims to evaluate the feasibility of using natural tuff found in the middle Anatolian region of Turkey for the removal of radioactivity from liquid radioactive wastes. Block samples that were collected from four different tuff deposits were first crushed to obtain particles with various sizes. The samples were then treated with low-level liquid radioactive waste in laboratory conditions. The effect of particle size on the adsorption performance of the tuff samples was studied for four types of radionuclides (241Am, 134Cs, 137Cs, and 60Co). The removal rates of radioactivity by the tuff samples having five different aggregate sizes (diameters of 4, 2.8, 2, 1, and 0.7 mm) were determined by the decrease in radioactivity concentration of the passed liquid discharge. In addition, the specific retention, saturation, and adsorption rates of the samples were also investigated. For most of the radionuclides, up to 50% saturation level and 70% specific retention were observed while the optimum results were acquired for the samples with 2 mm particle size.