An experimental program was formulated to investigate the influence of some factors affected the overall flexural behaviour of high strength under reinforced concrete beams lapped at tension zone. Fourteen beams were made from high strength concrete and only one beam made from normal strength concrete. These beams were tested under two point static loading to study the flexural behaviour of high strength concrete beams reinforced with spliced tension bars. The effect of concrete compressive strength, lap splice length, transverse reinforcement at lap splice and the percentage of tension reinforcement ratio on its behaviour were considered. Also, the experimental results were compared with those predicted values based on the available well-known theoretical equations. The tests showed that the increase of concrete compressive strength, transverse reinforcement at lap splice regions and lap splice length considerably improve the flexural behaviour of high strength under reinforced concrete beams.