This paper reviews the structural performances of reinforced concrete beams and slabs filled with lightweight materials to identify the research gaps in the area for future research development. Data is extracted from the research works done by different researchers. It was then recomputed to analyze the effects of concrete replacement regions, geometrical properties and spacing of lightweight materials on the ultimate strength of the structural elements. The lightweight materials were found to be more effective in reducing the weight of the slab without significantly affecting its strength as compared with the beam. The lightweight materials are recommended to have round corners, spaced out and positioned at the neutral axis or the compressive region for better strength performance so that the effective strength to weight ratio exceeds 1.0.