Individuals of the cestode species Ctenotaenia marmotae (Frölich, 1802) (Cestoda: Anoplocephalidae) possessing duplicated rudimentary ovaries toward the medial parts of the segments were found in material collected from the Siberian marmot (Marmota sibirica) in Mongolia. This tapeworm is characterized by possessing one pair of female genitals per segment. The extra rudimentary ovaries that we found ranged from 1 to 6 in number per segment and were much smaller than the main pairs of ovaries. Although multiplication of ovaries was reported to occur in a species of Diandrya (Darrah, 1930) by Rausch (1980), this is the first report of multiplication of ovaries in this species of cestode.