The minimum void concept was used to proportionhigh strength fly ash concrete.Numerous trial batches were made to determine the optimum mix proportion. Nine beams were cast from optimum mix to investigate theflexural behaviorof this type of concrete. The requirements specified in current ACI 318 for modulus of elasticity of concrete, modulus of rupture of concrete, flexural strength of beam sections, effective moment of inertia of flexural members, maximum tension reinforcement ratio and minimum tension reinforcement for seismic design were examined for their application to high strength fly ash concrete.