In 2008, 260 humanitarian aid workers were killed or injured in violent attacks. Such attacks and other restrictions substantially limit the ability of humanitarian aid agencies to provide assistance to those in need, meaning that millions of people around the world are denied the basic food, water, shelter and sanitation necessary for survival. Using the humanitarian crises in Darfur and Somalia as examples, this paper considers the legal obligation of state and non-state actors to consent to and facilitate humanitarian assistance. It is shown that the Geneva Conventions and their Additional Protocols, as well as customary international law, require that states consent to and facilitate humanitarian assistance which is impartial in character and conducted without adverse distinction, where failure to do so may lead to starvation or otherwise threaten the survival of a civilian population. This paper considers whether this obligation has been further expanded by the development of customary international law in recent years, as well as by international human rights law, to the point that states now have an obligation to accept and to facilitate humanitarian assistance in both international and non-international armed conflicts, even where the denial of such assistance does not necessarily threaten the survival of a civilian population.