The article uses documents covering the process of preparing and conducting by the NKVD bodies of the Ukrainian SSR a massive “German operation” – an integral part of the “Great Terror” in the USSR in 1937-1938. The historical circumstances of the appearance of the order of the NKVD of the USSR No. 00439 of July 25, 1937 and the specifics of its implementation in the Ukrainian SSR are disclosed. They also characterize the methodology for selecting the “contingent” that was repressed (victims of the operation), the technology of conducting mass repressions within the framework of the special operation and their tragic consequences for the German population of Ukraine. As the operation quickly gained momentum, it was not easy for German diplomats to figure out what was happening in Ukraine. But, as follows from the telegram of the German Embassy to Berlin on August 7, 1937, diplomats saw through the general situation in the USSR. They directly linked the arrests of German citizens “with well-known terrorist acts directed against all sections of the local population”. In other words, they saw and adequately evaluated the German component of what would later be called the “Great Terror” from the first days of the German operation. The documents that were used confirm that the tragic aspect of the beginning of the operation was the simplification and acceleration of the so-called “German affairs” investigation. The judiciary, in particular the military tribunals, which were not directly involved in the German operation but were involved in the consideration of cases against people, among whom were Germans – citizens of the USSR, did not lag behind the pace of “work, accused of such serious paragraphs of Article 54 of the Criminal Code of the Ukrainian SSR as treason, espionage, sabotage, terror. The sanction of this article in almost all cases provided for capital punishment – execution, which was widely used in practice. The last point in documenting the repressions against victims of this category was the NKVD bodies reports to the relevant military tribunal about the execution of the sentence of the tribunal. The prosecution authorities and, to a lesser extent, the USSR People’s Commissariat for Foreign Affairs contributed to the fight against “enemies”. The arrests of some German citizens were coordinated with them.