The endangered Mauna Kea silversword, Argyroxiphium sandwicense ssp. sandwicense (Asteraceae), has experienced a severe decline in distribution and abundance because of predation by alien ungulates. The small remnant natural population on the Mauna Kea volcano contains only 46 individuals. By contrast, the Haleakala silversword, A. sandwicense ssp. macrocephalum, consists of a large, vigorous population exceeding 60 000 individuals. Molecular genetic variation in the two populations was assessed using random amplified polymorphic DNA (RAPD) loci. Despite its severe crash in size, the Mauna Kea population did not differ significantly from the Haleakala population in the number of detectably polymorphic loci or in heterozygosity. The lack of substantial reduction in genetic variation, at least as measured with RAPD loci, suggests that the Mauna Kea population may not yet have gone through multiple generations at very small size.