What meaning does the notion of off-work have when employees, such as those at Médecins Sans Frontières (MSF), remain constrained by their uninterrupted work for months on end? Based on participant observation during a dozen of missions with MSF, and on the definition of off-work as a time to preserve intimacy, I argue that the notion of off-work is blurred at MSF on the one hand by the sharing of accommodation between colleagues, by the flexibility of working hours, by the presence of 24-hour safety rules or by the delegation of employees' health throughout their mission to the organization, but on the other hand by a motive underlying all the others: the issue surrounding the meaning of the word work, between constraining and fulfilling activity.