In the first part of a taxonomic revision of the tribe Barlerieae (Acanthaceae) in Angola and Namibia, two of the four major clades of the genus Barleria L. are studied in detail, namely subg. Barleria and subg. Prionitis sect. Prionitis. Using standard morphology-based taxonomic methods, a total of 32 species and 39 taxa are delimited, of which 12 are endemic to Namibia, nine are endemic to Angola, a further four are restricted to the two countries combined and four are largely confined to the region. Hence, nearly 70% of the taxa are endemic or near-endemic to Angola and Namibia. Full descriptions, citations of types and representative specimens, and notes on their habitat(s), ecology and biogeography are provided for each taxon. Seven new species (Barleria calole, B. crabbeoides, B. craveniae, B. deserticola, B. fernandae, B. namba and B. rupicola), two new subspecies (B. lanceolata subsp. tristis and B. prionitoides subsp. strigulosa) and one new variety (B. rigida var. spinissima) are described. In addition, Barleria namutonensis Oberm. is treated as a subspecies of B. prionitoides, and B. dinteri Oberm. is treated as a subspecies of B. coriacea Oberm. and the necessary new combinations are made, whilst B. schenckii Schinz is resurrected as a good species. Eleven names in Barleria are lectotypified. A preliminary assessment of the conservation status and extinction risk is provided for each taxon. Of the 39 taxa enumerated, the majority are assessed to be of Least Concern, but one is assessed as Endangered, four as Vulnerable, one as Near Threatened and six are currently considered to be Data Deficient. Keywords: IUCN, red list, assessment, Kaokoveld, lectotype, new species, taxonomy.