Three liana species of Grewia L. are described from Madagascar, bringing to five the members of the genus on the island to exhibit this habit. Grewia manomboensis G.E. Schatz, Randrian. & Lowry, sp. nov., G. rabehevitrae Randrian., Lowry & G.E. Schatz, sp. nov. and G. rufostellata Randrian., Lowry & G.E. Schatz, sp. nov., all three of which occur in low- to mid-elevation humid eastern forest, can be distinguished from one another by several features, including differences in the leaves (size, margin and prominence of the tertiary venation), pedicels (length, diameter and trichome density), sepal size, indument type and color, and petal shape. Illustrations are provided for each new taxon and photographs for two of them, along with a range map, preliminary assessments of the conservation status of each species, and an identification key in English and French.