Based on recent collections, we reported three new national records of ferns for Vietnam: Haplopteris yakushimensis, Lindsaea kohkongensis, and Pteris pseudowulaiensis. We conducted phylogenetic analyses to investigate the placements of Lindsaea kohkongensis and Leptochilus poilanei, each based on three plastid DNA markers. Our results revealed that Lindsaea kohkongensis is sister to L. ensifolia, while Leptochilus poilanei is embedded within L. cantoniensis. We discussed these results in the context of systematics. Lastly, we reported chromosome numbers for 20 fern species in Vietnam. For seven of these species, including Gymnosphaera salletii, Lepisorus spicatus, Leptochilus poilanei, Pteridrys costularis, Pteris latipinna, Pyrrosia eberhardtii, and Tectaria setulosa, these counts were recorded for the first time. Additionally, three new cytotypes were identified for Diplazium doederleinii, Pteris esquirolii, and Tectaria harlandii.