A new fern species, Tectaria danangensis (Tectariaceae) is described and illustrated from Vietnam, which had long been misreported as T. crenata. The new species somewhat resembles T. poilanei, a species long neglected in the fern flora of Indochina, in the frond shape and sori arrangement but differs by its sori irregularly in two rows (versus regularly 2-rowed, distantly and evenly arranged) between lateral veins of pinnae, fronds being more or less dimorphic (versus monomorphic), and basal pinnae each having a base-joined (versus free) branch. Phylogenetic analyses of selected sequences of cpDNA suggested T. danangensis has close affinity to T. harlandii. Tectaria danangensis appears to be an intermediate species between T. harlandii and T. poilanei.