Introduction:Failure of orthodontic bonded retainers may affect the orthodontic results and cause relapse. Objectives:To compare in vitro the effect of vertical load on failure of three different bonded lingual retainers:Flat braided wire "Bond A. Braid", Dead soft wire "RESPOND", Fiber reinforced composite "Infibra Ribbon". Bonded with Tetric-N Flowadhesive system. Materials and Methods:Ninetymandibular incisorswere used in the study, thirty specimens (N=30) in triads divided into 3 groups (n=10 for each group). Roots of the incisors were covered with elastomeric impression material to mimic periodontal ligaments elasticity and embedded in triads in acrylic resin blocks. They were randomly divided into 3 groups to receive the following retainer retainers between the three groups. There was no significant difference between the ARI of the lingual retainer systems and types of failure as well.