The purpose of this study is to investigate the effects of the type and amount of semiconductive fillers on the elastic properties of epoxy (ER) / semiconductive glass (SG) composites by ultrasonic velocity measurments. Different semiconducting glasses (SG) binary systems such as As2S3-TlS and As2Se3-TlS were synthesized. ER/SG composites were formed 15 wt. % of fillers and characterized by ultrasonic velocity measurments. The ultrasonic wave velocities of composites were measured with the pulse-echo method at room temperature by a flaw detector. The values of the acoustic impedance, Poisson's ratio, and elasticity constants of the samples were calculated by the measured values of both longitudinal and shear ultrasonic wave velocities. According to the results, The highest elastic properties values were found in the ER/SG-3 composite using 50% As2Se3-50% TlS. © 2014 AIP Publishing LLC.