Th e aim is to highlight the sixty-year period of continuous development of judicial and disciplinary practice of Ukrainian nationalist organizations. Methodological basis was the principles of scientific objectivity and historicism. General historical methods are also used: historical comparative, retrospective, problematic, structural. Th e scientific novelty is based on the analysis of the sixty-year development of the judicial and disciplinary practice of Ukrainian nationalist organizations. For the first time, the specified issue was comprehensively discussed and objectively covered in Ukrainian and foreign historiography. Probable prospects for the introduction of underground justice under modern conditions of war have been determined. Th e main results. Since the 1920-s, the judicial and disciplinary practice of Ukrainian nationalist organizations had been relying on the “challenges of the revolutionary struggle” and was regulated by numerous internal documents. Punitive actions usually fell into two categories. The first consisted of members and sympathizers of the underground, and the second-collaborators and agents of the enemy, mostly from the local population. Th e first consisted of members and sympathizers of the underground, and the second were the collaborators and agents of the enemy, mostly from the local population. During the 1940-s, a clear vertical of disciplinary bodies was introduced. It provided for the right to defense, appeal, and took into account the merits of the defendant, his position, the degree of guilt and the consequences for the underground. Most “revolutionary courts” or “tribunals” operated on the principle of extraordinary extrajudicial bodies (“dviiky”, “triiky”, “chetvirky”, etc.). Th eir obligatory components were: the chairman and the jurors. Prosecutors, defense attorneys, witnesses, and victims were also often involved. Sentences were usually severe. Especially if the defendant was prosecuted not for the first time. Th e death penalty was used against exposed enemy agents or individuals who caused significant damage for the underground. Minor offences were dealt with by “Cossack courts”, which were convened by the UPA commanders of insurgent units in the case of: drunkenness, failure to comply with an order (without serious consequences), petty theft s. Th e sentences passed by them were rather lenient -warnings, demotion, temporary suspension of membership, hard labor, increased drill with poor nutrition, fines, public beatings, etc. Th e judicial and disciplinary practice of the ZCh OUN, especially since the end of the 1950s, operated within the limits of the legislation of Western countries. In general, it focused on maintaining internal organizational discipline. [ABSTRACT FROM AUTHOR]