Each year large numbers of Western men travel to Thailand in order to engage in paid-for sex with female sex workers, a practice referred to as 'sex tourism'. While many male sex tourists use condoms during these sexual encounters, there is also evidence that some do not, potentially exposing themselves and others to the risk of acquiring sexually transmitted infections, including HIV. This thesis draws on data collected from 1237 online discussion board posts and 14 face-to-face interviews. It examines the ways in which Western heterosexual male sex tourists formulate their understandings of voluntary sexual risk-taking in relation to their masculinities and their perceived ability to control these risks. The findings suggest that many men value unprotected sex as an authentic and masculine practice, and believe that they can protect themselves from contracting sexually transmitted infections in other ways than by using condoms. The findings also demonstrate the role that setting and fantasy have on men's sexual risk-taking behaviours, and illustrate how beliefs and attitudes about gender and risk are constructed and maintained within locally reconceptualised masculine hegemonies. With female sex workers often disempowered to demand safer sexual practices, and men's attitudes towards unprotected sex deeply entrenched and resistant to external health promotion advice, the thesis concludes by considering what this means for theory, policy and practice, and suggests areas for future work that would further complement and enhance the findings of this study.