The past decade has seen the development of numerous arthroscopic techniques for ankle ligament repair or reconstruction in the treatment of chronic lateral ankle instability. Arthroscopy allows the assessment and treatment of intra-articular pathologies and is associated with faster functional recovery. The open surgery technique described by Blanchet, combining reinsertion of the lateral collateral ligament with reinforcement by an extensor retinaculum flap, has long proven its effectiveness. The aim of this article is to describe this technique under arthroscopy.