A series of polyepoxide resins doped by lead oxide with low concentrations were fabricated in order to study the impacts of low PbO concentrations on the fabricated composites' physical- and radiation-shielding properties. The epoxide resin was reinforced with the PbO compound with concentrations 0, 5, and 10 wt%. The density measurements affirmed that by elevating the PbO concentration between 0 and 10 wt%, the composites' density increased from 1.103 to 1.185 g·cm-3. This low-density increase was echoed in the fabricated composites' radiation-shielding properties, where the Monte Carlo simulation code affirmed a linear attenuation coefficient increase by factors of 230%, 218%, 24%, and 10%, respectively, at 59, 121, 356, and 662 keV. The half-value layer, mean free path, and transmission factor indicated a linear attenuation coefficient enhancement. © 2023 the author(s), published by De Gruyter.