In most general terms, hathayoga involves the internalisation and embodied literalisation of the Vedic fire sacrifice. Reflecting on the place of sacrifice in anthropological theory, and on the way in which sacrifice structures the relationship between humans and gods in terms of gift obligations, this paper explores the theoretical implications of hathayoga's embodied literalisation of a profoundly symbolic act. Although similar to various forms of ascetic renunciation, hathayoga is unique, it will be argued, in being structured as the physiological antithesis of religious ritual. Self-realisation based on the internalised yajna sacrifice undermines the binary structure of the sacred and the profane and makes god irrelevant. This raises theoretical questions concerning the social significance of a ritual that is anti-social on a number of different levels.