Red merantis (Shorea subgen. Rubroshorea) are the most important commercial trees of the Dipterocarpaceae. In Sumatra at least 23 of the 55 species of Shorea belong to this group. Other groups are the Yellow merantis, White merantis, and the Meranti balau. We here give a key to the Red merantis based on characters of bark, twigs, and leaves. Some information on the distribution of the species in and outside the island has been added. We have found it difficult with the data available in the published record to make distributions as detailed as possible. Desch (1936, 1941) and Symington (1943) have divided Shorea Gaertn. into four groups based on timber and field characters, respectively. These groups were treated as subgenera by Meijer (1963), who gave the name Rubroshorea to the most well-known group of the Red Meranti. Anatomical studies by Gottwald and Parameswaran (1966) have confirmed the soundness of this classification.