Four new Asian taxa are described and illustrated as part of a forthcoming taxonomic revision of the cultivated species of Begonia (Begoniaceae). The new species B. argenteomarginata (sect. Symbegonia) is described from Papua New Guinea. Two new species from section Petermannia are described: B. polilloensis from the Philippines and B. rachmatii from Sulawesi, Indonesia, both of which are unusual in having palmately compound leaf blades. A key is provided for these and a previously described species, B. oligandra, also with palmately compound leaf blades and in section Petermannia. The new subspecies B. brevirimosa subsp. exotica (sect. Petermannia) is described from the Central Range of Papua New Guinea and a brief history of its cultivation is presented.