A detailed review of available literature in external prestressing in particular to the behaviour of beams and assessment at ultimate is done. The behaviour of external post tensioning beam is different from the bonded prestressing due to the strain incompatibility condition. The effect of external tendons in either a pre-cracked beam or in a new beam (both in flexure and shear) is reviewed. Various researches parameterising the geometry of tendon profile, effect of deviator blocks, level of strain in internal passive reinforcement, loading types, effect of initial crack widths, combination of external prestressing and fibre wrapping and the increase in tendon stress at ultimate, is reviewe. © IAEME Publication.