Flexor tendon lacerations still represent a challenging problem to hand surgeons, particularly in zone 2. There has been a considerable improvement in therapeutic modalities during the past 30 years, following a better understanding of the tendon healing process. It is now universally accepted that flexor tendon repair must be performed in emergency, by mean of a direct primary suture, and followed by a immediate rehabilitation protocol. More recently, the benefits of early active motion has been demonstrated. Early axial loading of the repair enhances intrinsic callus formation, reduces peritendinous adhesion, and could attenuate the fragilization of the callus during the first three weeks. However, active motion generates a heavier stress on the repair. The initial resistance of the repair thus appeared to be the critical point. This has motivated a large number of investigations about the suture technique itself, with in vitro and in vivo evaluations. The results of these studies did precise the concept of "locking" and "grasping" sutures, and demonstrated the superiority of four strands sutures. These experimental results cannot be ignored by surgeons dealing with flexor tendon repairs.