Flowers of the early Polyantha roses, ‘Pâquerette’, ‘Mignonette’ and ‘Anne-Marie de Montravel’, have an unusual odor not found in other roses. Their ancestor is Rosa multiflora, a wild species native to Japan. In particular, ‘Anne-Marie de Montravel’ has a citrus scent with an old wooden closet-like odor. Gas chromatography (GC)-mass spectrometry analysis of the scent components of these roses revealed the presence of several terpenoids, benzenoids, and hydrocarbons, as well as the fatty acid derivatives methyl (E, Z)-2,4-decadienoate (MDD) and methyl (E, E, Z)-2,4,6-decatrienoate (EEZ-MDT). GC-olfactometry analysis of scent components of ‘Anne-Marie de Montravel’, identified EEZ-MDT and its isomers as the source of the unpleasant odor. MDD and EEZ-MDT are known as stink bug pheromones, but they were first detected in the scent of plants. We also analyzed the floral scent of several roses related to R. multiflora, namely: two plants of R. multiflora, two Hybrid Multiflora roses (‘Crimson Rambler’ and ‘Rose-Marie Viaud’), eight Polyantha roses (‘Cécile Brunner’, ‘Clothilde Soupert’, ‘Gloire des Polyantha’, ‘Madame Norbert Levavasseur’, ‘Marie Daly’, ‘Marie Pavié’, R. multiflora ‘Nana’, ‘Yvan Misson’), and one Miniature rose (‘Gourmet Popcorn’). EEZ-MDT and/or its isomers were detected not only in ‘Marie Daly’, ‘Marie Pavié’, R. multiflora ‘Nana’, and ‘Gourmet Popcorn’, which had an old wooden closet-like odor, but also in R. multiflora, ‘Rose-Marie Viaud’ and ‘Yvan Misson’, which do not exhibit that unpleasant odor. To produce the unusual odor in the rose fragrance, the EEZ-MDT and its isomers content must be above a certain percentage of the scent components.