Clinical research is increasingly ‘offshored’ to developing countries, a practice that has generated considerable controversy. It has recently been argued that the prevailing ethical norms governing such research are deeply puzzling. On the one hand, sponsors are not required to offshore trials, even when participants in developing countries would benefit considerably from these trials. On the other hand, if sponsors do offshore, they are required not to exploit participants, even when the latter would benefit from and consent to exploitation. How, it is asked, can it be worse to exploit the global poor than to neglect them when exploitation is voluntary and makes them better off? The present article seeks to respond to this challenge. I argue that mutually beneficial and voluntary exploitation can be worse than neglect when — as is typically true of exploitative international research — it takes advantage of unjust background conditions. This is because, in such cases, exploitation overlaps with another, less familiar wrong: complicity in injustice. Recognising complicity as a distinct wrong should make us judge exchanges arising from background injustice more harshly than we typically do, in research and elsewhere.