The article analyses documents from the Central State Archive of Moscow (TsGAMo) that concern the events of the summer of 1915 when, with police inaction, if not sufferance, the patriotic demonstrations erupted into riotous disturbances and pogroms of the premises of German and Austro-Hungarian citizens and even of Russian ones bearing German names. There were fatalities. The author notes fragmentarity of data that should have been preserved in Moscow state agencies, such as offices of the Mayor, the city police, and the State Duma. He ventures a guess on who and when had the documents concealed or destroyed. Countermeasures against mob outrages and ways of reinstalling orderliness of social life in Moscow were discussed in the State Duma. Several deputies gave speeches and there was a decision ‘to concede the need for immediate investigation.’ The minutes only lists the names of speakers, when there should have been verbatim records. On the meeting on June 2, 1915, the Mayor reported that 476 industrial and commercial premises and 217 lodgings had suffered pogroms. 113 German and Austro-Hungarian citizens had been injured, as well as 485 Russian citizens bearing foreign names and even 90 bearing unexceptionable Russian names. That is all data on the anti-German disturbances in Moscow on May 27-29, 1915 (which was an event of great importance), that have been preserved in the Central State Archive of Moscow. Probably, some information may be obtained in the Russian State Military History Archive (fonds of the Moscow military district staff and its court martials and those of the military censorship). The major array of sources should have been deposited in the papers of the Senate commission headed by N. S. Krasheninnikov. It was created on June 8, 1915 in order to investigate causes and initiators of the pogroms. The investigation resulted in discharge of High Commissioner Yusupov and in committal of City Governor Adrianov and Polizeimeister Sevenard for trial.