An examination of the use of medical simulators shows that they contain traces of the one-sex body model found in pre-Enlightenment anatomies. The simulators present the male body as 'male including female' rather than 'male, not female'. Only when female sex organs are relevant to a practice, as in gynaecology, does a simulator need to become 'female, not male'. The widely held modernist understanding of sex and gender as binary categories is actually masking local practices which allow varied sex and gender paradigms to coexist in simulator use. This analysis applies the discussions of Laqueur, Schiebinger and Faulkner to simulator practice. The consequences of recognizing the presence of the one-sex body are two-fold. Firstly, seeing that the relocation of medical knowledge can still be haunted by conceptual paradigms of the past forces a more nuanced understanding of the variety that localized medical practices contain. Secondly, observing the ease with which the reified knowledge of a one-sex body is embraced by subjects who also exist in a world of binary gender points to the complexity our subjectivities can embrace and forces the researcher to acknowledge the implications of the simulations' context. Copyright © 2005 SAGE Publications.