The species diversity of the family Xylariaceae in Ru Linh, Vinh Linh district-Quang Tri province is very high. Up to now, 14 species belonging to 3 genera: Daldinia. Hypoxylon and Xylaria have been recorded. Among 3 identified genera, the genus Xylaria is most abundant taxon, including 12 species (85 percent of the all identified species). Among 14 identified species, there are 2 new species to the macromycoflora of Vietnam (Hypoxylon pseudopachyloma Speg.. and Xylaria euglossa Fr.). Most of the species of the family Xylariaceae are saprophytic species destroying woods: Daldinia concentrica. Xylaria grammica, Xylaria plebeja...Some species of the family Xylariaceae are medicinal mushrooms: Daldinia concentrlica, Xylaria polymorpha... Many species of the family Xylariaceae can synthesize a diverse range of metabolites which often possess biological activity. The crude extracts from some of Xylariaceae have antimicrobial activity against Salmonella.