This paper analyses evidence for the practice of surgery, as opposed to its theory, in the Islamic Middle East at the end of the first millennium. The inclusion in formal Arabic medical treatises of complex or invasive surgical procedures is compared with the lack of evidence for their actual performance, as well as with statements to the effect that such techniques were unknown at that time or should be avoided. Areas in which there is greater evidence of the practice of surgery-such as the removal of superficial growths and the treatment of eye diseases-are also discussed. In particular, the paper focuses upon treatises by 'Abū al-Qāsim al-Zahrāwī (known to the Europeans as Albucasus), Abū Bakr Muhammad ibn Zakarīyā' al-Rāzī (Rhazes), 'Alī ibn al-'Abbās al-Majūsī (Haly Abbas) and Ibn Sīnā (Avicenna).