The functions of the biblical Slavic-Russian apocrypha in manuscript collections depend on their perception by the ancient Russian scribes and the literary context of the manuscript. Cognitive, interpretative, magical, historical functions are associated with different genre forms, both book and folk. Particularly considered is the «apocryphal riddle» of two brothers from the manuscript of the XVIth century Stockholm Royal Library and manuscripts of the XVIIIth century collections of the Library of the Russian Academy of Sciences (St. Petersburg).