The paper continues our recent publication of new original data on orchid diversity in Vietnam (Averyanov and Gruss, 2018a-d; Averyanov et al., 2018a-e; Gruss et al., 2018) obtained in 2017–2018. It includes data on 3 orchid species new for science (Coelogyne dolichopoda, Liparis robustior and Oberonia khuongii) and 5 species, new for the flora of Vietnam (Epigeneium nakaharae, Liparis bistriata, L. rhodochila, L. siamensis and Nervilia mackinnonii). Annotated species list provides the valid name, synonyms, type, citations of relevant taxonomic regional publications, data on ecology, phenology and distribution, estimated IUCN Red List status, studied specimens, brief taxonomic notes, and illustrations for each recorded species. Lectotype for Liparis siamensis is designated.