Several extra-Vietnamese names have been misapplied to Vietnamese Begonia species. For those included by Gagnepain in Flore générale de l’Indo-Chine, Begonia aptera is B. acetosella Craib and B. rex is B. sizemoreae Kiew; B. rupicola and B. wallichiana are new species, here named B. phamiana Kiew and B. glutinosa Kiew, respectively. Four included by Hô. in Cây Cô Viêt Nam whose identity cannot be verified, namely, B. decora, B. grandis, B. martabanica and B. masoniana are excluded from the checklist of begonias from Vietnam. Begonia poilanei Kiew, a striking new species with ornamental potential, is also described.