Currently, the genus Chimarra Stephens (Trichoptera: Philopotamidae) is represented in the Oriental Region by 259 species. Of these, 61 species have been described or recorded from Vietnam. In this paper, 9 new species from Vietnam are described and illustrated (Chimarra aculeata, C. carinata, C. corneola, C. insolita, C. mina, C. prominens, C. rostrata, C. undulata, and C. ungula). In addition, 3 new country records are noted (Chimarra areli Malicky and Mey, Chimarra pipake Malicky and Chantaramongkol, and Chimarra suthepensis Chantaramongkol and Malicky), and 1 new species group (minuta Group) is proposed and populated. An additional species group (georgensis “Group”), with 1 new species from Vietnam, but otherwise only known from Africa, is discussed, but not formally defined. A table listing all known Vietnamese species of Chimarra is included, along with discussion of variability in the anal veins of the forewing found within this genus, and its relevance for defining subgenera and species groups
