Is it ever reasonable to accept the claim that a miracle has occurred? At least for fairly traditional Christians, this question has a special point, since their faith is centred upon acceptance of a miracle, the resurrection of Jesus from death. If it is unreasonable to accept any claim to the occurrence of that miracle, then their faith is ipso facto unreasonable. J. L. Mackie has recently propounded an argument, based closely on David Hume's essay on miracles, in part 10 of the Enquiry concerning Human Understanding, which provides, he says, ‘a very powerful reply to any claim that a miracle has been performed’ (The Miracle of Theism, 26). My aim is to examine his argument, and to make some comments on his understanding of the notion of miracle and its place in religious belief.