Tail docking of new born lambs is a routine practice in the United Kingdom. It has been used as a strategy to reduce the impact of myriasis (blowfly strike). There is only a limited period of time after birth (up to seven days) during which lambs can be docked without the use of anaethesia. Tail docking may have a detrimental effect on the ewe-lamb bond if the process leads to significant and sustained pain. French, Wall and Morgan (1994) suggested lambs suffer acute pain immediately after the procedure of docking but this potential disturbance of normal behaviour during the first few days of life did not seem to affect the long-term performance of lambs. The study reported in this paper considers the effect of tail docking on the behaviour of lambs during the first 90 minutes after docking and on lamb performance to slaughter.