Random amplified polymorphic DNA markers (RAPD) were used to assess the genetic relatedness among accessions of four species of Desmodium and allied genera (Dendrolobium triangulare, Desmodium gangeticum, Desmodium heterocarpon ssp. heterocarpon, and Tadehagi triquetrum) originating from Northeast Vietnam. Since information on the genetic diversity of these species is deficient, the creation of baseline data is an important means for the development of more sustainable and cost-efficient conservation approaches which eventually result in more comprehensive ex situ germplasm collections. The species analyzed are native to tropical and subtropical Asia, Australia, and Oceania and possess a potential as forage and/or medicinal plants. Moderate levels of inter-accession diversity represented by 37.5% and 33.3% of polymorphic fragments (P%) and average Jaccard's similarity coefficients (JSCs) of 0.60 and 0.64 were found in D. heterocarpon and T. triquetrum, respectively, while moderate to high levels were detected in D. triangulare (P% = 52.9 and JSC = 0.61) and D. gangeticum (P% = 34.5 and JSC = 0.49). Mantel tests failed to reveal a correlation between geographic and genetic distances. Based on the results of this study, baseline data for further marker-assisted research are generated and future collecting and ex situ conservation strategies for the species studied are discussed.