In past decades, much progress has been made in responding to health-care needs of conflict-affected populations. The evidence base for interventions addressing excess morbidity and mortality has expanded. Motivated by a disastrous response to the Rwanda genocide in 1994, the Sphere standards for service provision were developed, fostering quality and accountability on the basis of principles of do no harm.Overall, mortality has decreased in refugee camp settings. A new cluster approach to improve coordination of relief outside of refugee situations has been introduced. However, humanitarian space—physical locations that are safe from attack in a conflict, respect for core humanitarian principles of independence, impartiality and neutrality, and the ability of aid agencies to access and help civilians affected by conflict—has shrunk substantially because of political polarisation and a perception by combatants that humanitarian assistance is merely an instrument of interference by foreign powers. These factors have had negative effects on the protection of both people affected by conflict and humanitarian workers, and consequently have affected the ability of organisations to provide preventive and curative health services because of insecurity.