There has been a significant amount of discussion on the applicability of international humanitarian law (IHL) to United Nations forces (hereafter, UN forces), and the practice of the UN and states on the matter has gradually developed over the years. Now, there is substantial evidence that IHL is applicable to UN forces. However, as alleged misconduct of UN forces has been increasingly reported, including potential violations of IHL, the legal consequences of such violations have come into question. Thus, this article will not only review the recent developments and remaining issues on the applicability of IHL to UN forces but will also discuss the responsibility of the UN and states for violations of IHL by UN troops as well as individual criminal responsibility of UN troops. The article begins by recalling the conditions in which UN forces have been conducting their activities.