Erodium cicutarium (L.) L'Herit. (Geraniaceae) originating in Mediterranean Europe is here reported for the first time from Taiwan. This newly naturalized species differs from E. moschatum (L.) L'Herit, first recorded in Taiwan in 1992, by having deeply cleft leaflets and pointed sepals with an apical extension of the midrib. The taxonomic treatment of E. cicutarium and a key to species of Erodium in Taiwan are given in this study.