This paper explores Nigerian undergraduate students' perspectives of gender influence on sexual risk-taking. Participants were recruited from several peer networks with snowballing because female students initially refused to participate in a long interview about their risk-prone sexual conducts with a male investigator. Analytically, essentialist notions of gender, such as hegemonic masculinity or passive femininity, were interrogated against the backdrop that they determine women's vulnerability to sexually transmitted infections (STIs) and unwanted pregnancies in heterosexual relationships. There were tensions and contradictions between respondents' narrative self-presentations as knowledgeable, purposeful, and active social agents capable of elective sexual choice, and as agents whose sexualities are concurrently constrained and enabled by a cohort of interdependent societal structures, including gender, whose unitary influence on sexual risk-taking they consider weak. All respondents concede that their purposive and active pursuit of premarital heterosexual relationships, especially their maintenance with unprotected sex, is a stronger determinant of their vulnerabilities to STIs and unwanted pregnancies than the gender structure alone. Unequivocally, findings challenge essentialist notions of feminine sexual passivity and exclusive masculine sexual privilege, within premarital heterosexual relationships. Consequently, the author calls for the re-examination of gender structure on patterned behavior based on specified social interactions, such as premarital heterosexuality.