This essay explores the ways in which emerging religious understandings of sexual reassignment surgery (SRS) have potential for new work in comparative ethics. I focus on the startling diversity of teachings on transsexuality among the Vatican and leading Shia clerics in Iran. While the Vatican rejects SRS as a cure for transsexuality, Iranian clerics not only support decisions to transition to a new sex, they see it as necessary in some cases given the gendered nature of the moral life. In (...) this essay, after describing the practical justification for sexual reassignment surgeries in Iranian fatwas and the emerging official Vatican position on transsexuality, I explain how these divergent positions are based on different semiotics of sex and gender that reflect specific ontological views of the human body. (shrink)