The article is about research on the questions about the ethnodemographic history of the Pelym's Mansi, Pelym dialect native speakers that were assimilated into Russian environment and lost their ethnic identity in the middle of the XXth century. The author traces the history of their surnames and in connection with this shows the role of the Sosva Mansi in forming the Mansi populace on the river Pelym. Some surnames are examined from the etymological point of view. This work is based on the historical data, anthroponimic and toponimic material of the written and fi eld sources.