South Korean women are less favourable towards open admission policies for North Korean defectors, less supportive of assistance to defectors, and less willing to integrate with defectors than are South Korean men. Such a gender gap contradicts the findings of studies on refugee attitudes in Western countries. This article proposes two distinct explanations for the gap: 1. intra-gender competition induced by a gendered labour market and gender-imbalanced defector inflows and 2. gendered outgroup attitudes where women show greater anxiety and aversion towards an unfamiliar outgroup than do men. The explanations are tested using annually repeated cross-sectional survey data (2007–18). I find more consistent support for the gendered outgroup attitude explanation. Whilst South Koreans of both genders increasingly see the two Koreas as socio-culturally distinct, such perceptions of otherness are more strongly linked to negative defector attitudes among South Korean women. I also provide first-cut evidence that knowledge of North Korean society and politics mitigates the outgroup anxiety and, in turn, can mitigate the gender gap in defector attitudes. These findings hold implications for defector and refugee policies in South Korea and other refugee host countries in the region.