Several factors affect the behavior of concrete used in structural elements such as columns or beams. One of the primary factors that affects the behavior of concrete is the characteristic properties of the aggregates used in the mix proportion. The main purpose of this study is to investigate and compare the behavior of lightweight and ordinary concrete produced with lightweight and ordinary aggregates in selected reinforced concrete beams. In the first part of the study, brief information is given about the use of lightweight concrete in structures. In the second part of the study, properties of materials used in the production of beams selected for this study are discussed. In the third part of the study, the production stage of selected lightweight and ordinary reinforced concrete beams is explained. Some conclusions drawn from this study are presented in the final section. The results of this study show that the use of lightweight concrete in reinforced concrete beams is more suitable than the use of ordinary concrete. DOI:10.1061/(ASCE)MT.1943-5533.0000465. (C) 2012 American Society of Civil Engineers.