The longstanding friendship between the Yakovlev and Ulyanov families is a wide-ranging topic. The Ulyanov family has been thoroughly studied by historians, but the Yakovlevs did not enjoy comparable attention. The most renowned of this last clan was Alexey Ivanovich Yakovlev, who kept up relations with Vladimir Lenin. But in the light of archival materials and memoirs, one could claim that interfamily relations extended beyond familiarity between these two individuals. The paper traces friendship between Alexey Ivanovich Yakovlev and Dmitry Il'ich Ulyanov. These friendly terms lasted for decades, since the childhood of the confidants, who maintained warm relations despite the circumstances and the vicissitudes of their fates. The source for the study of their friendship is the correspondence between them. A number of letters from both have been published, and the rest are in the Archive of the FSB Directorate of St. Petersburg and the Leningrad Region, in the investigative file of A. I. Yakovlev, who was arr