The aim of the article is to present the idea, genesis and functions of international non-governmental organisations in the contemporary world, a short characteristics of selected organisations that are active on the international arena, also an attempt to locate non-governmental organisations in joint operations and drawing some conclusions and rules basing on observations and experiences in this area. Alvin and Heidi Tofflers called non-governmental organisations „global gladiators of the 21st century”. They more often participate in joint operations in conflict regions and become natural partners for military forces in performing their military missions. They carry out tasks in all aspects of humanitarian aid, including legal services, assistance in crisis situations, help for refugees, especially women and children. They are included in various activities such as education, technical projects, actions for maintaining public order and development programmes.