International relations literature is well developed on the effects of United Nations intervention on the duration of crises. The global human rights community has on a case-by-case basis addressed some of the unintended effects of UN intervention, namely, substantial increases in the human sex trafficking trade into crisis areas. We bridge these two literatures and evaluate the effects of UN involvement in Kosovo, Haiti and Sierra Leone. We look beyond the intended effects of UN intervention and consider the unintended effects in a systematic and generalizable way. We argue that UN involvement has the unfortunate and unintended effect of increasing the rates of human trafficking in these crisis areas. Our work concludes that the UN should proceed with caution into crisis areas and have plans in place to avoid the potentially devastating externalities of otherwise well-intentioned efforts.