The main goal of this book is to study the effect of carbon nanotubes on the behavior of reinforced concrete beams under monotonic loading. In this study seven beams were loaded up to failure under the effect of a two- concentrated load where the failure mode was observed and the load-deflection relationships have been reported. Reference beam was reinforced with steel bars only while the other six beams were reinforced with short and long multi- walled carbon nanotubes MWCNTs at different concentrations of (0.03%, 0.045%, and 0.06%) by weight of dry cement in addition to steel bars.