The paper traces the historical background of the formation and development of the institution of international fact-finding. As a result of the progressive development of international law, the institution of international investigation emerged at the turn of the 19th and 20th centuries, first receiving its international legal consolidation in the Hague Convention on the peaceful settlement of international disputes of 1899. The history of establishing fact-finding bodies by states, which acted as parties to disputes based on factual issues, both at the universal and regional levels, is examined. The practice of resorting to investigation procedures within international intergovernmental organizations such as the League of Nations, the UN, ILO, ICAO, the World Bank, the EU, and others is considered. In the modern period of international law, the fact-finding procedure has gained quite extensive use and is implemented in a more primitive form, especially within the activities of the United Nations. The UN establishes international commissions (composed mainly of individuals who are not citizens of the parties to the dispute or participants in the situation) authorized, as often happens, not only to establish facts (conduct investigations) but also endowed with broad competence to provide conclusions on legal issues and recommendations for dispute resolution or situation. The UN also uses the international investigation procedure in conjunction with other international mechanisms for dispute resolution. Referring to international bodies for fact-finding, as one of the means of peaceful settlement of international disputes, was first provided for by the Hague Conventions on the peaceful settlement of international disputes of 1899 and 1907. Therefore, the existence of various nature international investigating commissions - from "pure" fact-finding in the Tigre case to investigations regarding the Red Cross and the Letellier and Moffitt case, which were close to arbitration.