The object of the study is the texts about Tan-varp-ekva, «the tendon twistress», recorded during the 20th c. The majority of the full-text tales has been recorded from the northern Mansi (Lyapin River Basin, Upper Lozva), some folklore stories have been published for various groups of Khanty (Yugan, Middle Ob, Berezovo, Kazym, Upper Purov, Shurishkar); the Nenets legend about the old woman-Sihirtia stands out. The tales mostly split into two plots: the first one is associated with the prohibition to spin veins at night, the second — with changeling and kidnapping of children. The analysis of the key points of the legends has been carried out, the position of the Ob-Ugorsk forest spirit among similar images of the Komi and Russians has been determined. The authors suggest that the village of Lombovozh (Lyapin Mansi) became the place of creation of the folklore storyline, linking it to the presence of a large archaeological site, a medieval settlement. The spread of the legend of Tan-varp-ekva among other Mansi and Khanty groups was the result of migrations. The main plot of the story refers to the introduction of regulations by the Ob Ugrians on inclusion of a daughter-in-law, young women into the foreign cult community. The story with a silver cup explains the rules of entry of a newly manufactured or brought from the outside object into the sphere of worship in the Ob Ugrians. Tan-varp-ekva in the role of a female deity could act as the patro-ness of needlework, as, for the Ob Ugrians, twisting of deer tendon threads was a traditional female work. The stories about Tan-varp-ekva are similar to those of many Russian fairy tales, ballades about mythical spin-stresses, as well as bans on needlework during the night and transition time. Her image has a lot in common with Baba Yaga and with the character of Yoma — her double in Komi (forest spirits, creatures of the lower world, kidnappers of children, cannibals, treasure keepers, treasure givers, «spinning» deities). The motifs of killing and eating of daughter-in-law by the spinstress of tendons can be an allusion of the rite of transition to a new family, when the girl «died» for her former family and left the protection of the spirits-keepers of her family. The popular-Christian layer of views of the Russians and Komi provides material for comparative analysis of mythological con-cepts of Slavic and Finn-Ugric peoples, who for a long period experienced mutual influence on ethnocultural tradi-tions. The function of Tan-varp-ekva as a «twister of tendons» can be secondary, borrowed from neighboring populations, for example, from the Komi, who, together with Orthodoxy, accepted and adapted the popular-Christian beliefs of the Russians.