Providing an opening in beam makes cracks surrounded the opening due to stress concentration. In this study an experimental works conducted to study the behavior of reinforced HSC T-shaped beams with flange opening in bending zone. This paper shows the behavior of RC beam with opening un-strengthened by additional reinforcement. In this experimental study three beams were casted, one rectangular beam and one T-beam without opening as a reference beam and the remaining beam was provided with one rectangular flange opening 180×360 mm at middle section. These beams were tested under one-point loading. The effect of flange opening was studied in terms of ultimate failure load, maximum deflection and failure mode. From the test results, it could be concluded that the ultimate load carrying capacity of the RC T-shaped beam with flange opening at flexural zone was reduced by about 2.30%. As well, the cracking load was reduced by about 2.94%.