We report a case of acute (24 h) double flexor tendon rupture of the little finger after a single injection of collagenase clostridium histolyticum into a palmar Dupuytren's contracture cord which caused metacarpophalangeal joint contracture. Tendon surgery was performed 48 h postinjury with primary repair and standard rehabilitation but it resulted in poor active flexion due to adhesions. Previous papers have suggested that a needle inserted into the flexor tendon can be detected prior to the injection of collagenase by asking the patient to actively move the finger, but our test on an awake patient showed that when a 27-gauge needle was inserted into the flexor tendons through a thick palmar cord, the syringe did not move significantly when the patient moved the finger, and therefore this test does not minimise the risk of iatrogenic tendon injury when using collagenase (Xiapex) for Dupuytren's contracture.