Eleven species of lichenicolous fungi are recorded from Bi Doup-Nui Ba National Park in Vietnam. Capronia josefhafellneri growing on apothecia and thallus of Septotrapelia triseptata is described as new to science. It is characterized by comparatively short setae up to 30 μm long and (0 –)1(–2)-septate ascospores. Clypeococcum rugosisporum and Zwackhiomyces diederichii are reported as new to Asia, and Abrothallus usneae, Arthophacopsis cf. parmeliarum, Lichenoconium erodens, Pseudoseptoria usneae and Roselliniella cladoniae new to Southeast Asia. Arthophacopsis cf. parmeliarum is found on Hypotrachyna species. Key words: Biogeography, lichen-inhabiting fungi, South Vietnam, taxonomy, tropics.