When fastener holes are made in structural beams, the Canadian Steel Design Code CAN/CSA-S16.01 -Clause 14.1 (CSA, 2003) states that no deduction in flexural strength is needed for holes up to 15% of the gross flange area. This clause was established many years ago, however, over the years the mechanical characteristics of structural steel have changed. This research program focuses on the effects of flange holes on the flexural behaviour of ASTM A992 grade steel beams. This paper presents an experimental investigation involving 25 beam specimens, on the effects of flange holes on the flexural behaviour of steel I-beams. Holes of various diameters, ranging form 0% to 48% of the gross flange area were laid by drilling holes (a) in the midspan of the tension flange and (b) in the midspan of both the tension and compression flanges. In addition, beams with holes filled with fasteners were also performed. Based on the experimental test results, this research study recommends a design approach analogous to the axial tension member provisions as per the current CAN/CSA-S16.01 (CSA, 2003) standard. In that, the effects of holes in regards to the flexural strength can be ignored if the gross-section plastic moment is greater than the factored net-section fracture moment hence, the beam member shall be designed to carry the gross-section plastic moment. Otherwise, the beam members shall be designed to carry the factored net-section fracture moment. The comparison of the recommended procedure with the 15% exemption rule as per current steel standard S16.01 (CSA, 2003) demonstrated that the current code provision is unnecessarily conservative for steel grades such as A992 steel. On the other hand, the current code provision may be more unconservative for high strength steels such as HSLA 80 steel, ASTM A913 Gr: 60 and HPS-485W having the minimum yield-to-ultimate strength ratio of more than 0.85.