The Renaissance sceptic and medical doctor Francisco Sanchez has been rather unduly neglected in scholarly work on Renaissance scepticism. In this paper I discuss his scepticism against the background of the ancient distinction between Academic and Pyrrhonian scepticism. I argue that Sanchez was a Pyrrhonist rather than, as has been claimed in recent years, a mitigated Academic sceptic. In keeping with this I shall also try to show that Sanchez was crucially influenced by the ancient medical school of empiricism, a school closely allied with Pyrrhonism.