This article examines the relationship between legitimacy and the presence of both male and female judges on international criminal court benches. It argues that sex representation – an approximate reflection of the ratio of the sexes in the general population – on the bench is an important contributor to legitimacy of international criminal courts. First, it proposes that sex representation affects normative legitimacy because men and women bring different perspectives to judging. Consequently, without both sexes, adjudication is inherently biased. Second, even if one rejects the proposition that men and women "think differently", sex representation affects sociological legitimacy because sex representation signals an impartial bench and capacity to do justice to constituencies involved in the shaping of international criminal adjudication. The article concludes by raising questions for further study.