As Fischer Tinè pointed out, “ poor whites or ‘low Europeans’, as they were called in contemporary administrative discourse, generally represented a serious menace to the legitimacy of colonial rule’. […] According to ethnic or ‘civilisational’ criteria, the groups in question were part of the ruling race and yet they figured among the ‘depressed and downtrodden’ in terms of class and hence of economic and political power” ( Fischer Tinè, 2003, p.164-5 ) This was all the more true for sex workers, as sex and gender constituted powerful facets of the bio-political power which became a distinctive feature of late Victorian empire and gender specific bourgeois roles and notions of decorum were adopted as standard of civilization and racial superiority. While professional sex workers were considered as socially dangerous and disruptive in the metropolitan context as well, in the colony their existence was even more problematic, as constantly calling into question notion of race purity and superiority the Imperial enterprise increasingly came to repose on towards the end of the Nineteenth Century. The embarrass felt by imperial authorities and middle class reformers for the presence of such liminal characters, unaccompanied women roaming the world in search of a living, was but the imperial dimension of the veritable social hysteria which originated around the so-called “White-Slave Trade”, the symptom of a more profound social and political crisis. After a brief analysis of the emergence of metropolitan obsession around the so-called “White Slave”, this paper will explore the colonial dimension of social purity, to show how a specific category of subaltern social actors, foreign prostitutes and ‘fallen’ women in Cairo, came to play a very important role in the preservation of besieged category of colonizers’ racial and civilizational superiority, through the creation of a specific apparatus of coercion, control and, possibly, regeneration managed by British social purity and feminist movements – namely the NVA – National Vigilance Association and the AMSH, Association for Moral and Social Hygiene – in Cairo between the I and the II World War.