The button-over-nail technique is commonly used to fix the core suture to the distal phalanx for flexor digitorum profundus repairs in zone 1. We report a retrospective study of 23 consecutive patients who had a repair of the flexor digitorum profundus tendon in zone 1 using the button-over-nail technique. Fifteen patients experienced a complication, of which ten were directly related to the button-over-nail technique. Complications included nail deformities, fixed flexion deformities of the distal interphalangeal joint, infections and prolonged hypersensitivity. Two patients required amputation of the fingertip. We recommend that the button-over-nail technique should be avoided or used only with caution and with close attention to the details of the technique.