Anthropogenic factors over the last 10-15 years have exerted negative influences on natural plant kingdom, causing an increasing degradation of forest, steppe, aquatic biotopes, etc. – fact which has caused significant changes related to the number of plants and population viability, habitat loss or expansion. The Law on the Red Book of the Republic of Moldova (25.01.2006, no. 432-IV) provides a series of articles on protection and restoration of objects of the Red Book (R. B.), updating the R. B., organizing state monitoring of R. B. objects, editing and publishing the R. B. (every 10 years), etc. While preparing the Red Book of Republic of Moldova (RBM), 3rd edition, for publication, during 2012-2013, field and laboratory researches on the current status of rare species of wild flora, assessment of habitat quality, number of plants in populations and limiting factors acting on native flora were conducted. As a result of the conducted research, highly threatened species were highlighted and a list of species proposed for the RBM, 3rd ed., was made. The evaluation of rare species and their categorisation was done according to the criteria adopted by the International Union for the Conservation of Nature (2001, 2003). The selection of species proposed for the respective edition was based on the following criteria: taxonomic – from taxonomic point of view, safe taxa were selected; the dubious and unclear ones were left for further study; specific spreading area – species with restricted and disjunctive specific spreading areas, endangered species; boundary of the specific spreading area –  species that are near or at the boundary of the specific spreading area, situation characteristic of most species; species that are found in few localities and geographical areas; species mentioned in international conventions etc.  Further, we present the list of highly threatened species, included in RBM, 3rd ed., proposed by the authors for state protection: Critically Endangered (CR) – Carex rhizina Blytt ex Lindb. (Cyperaceae), Centaurea salonitana Vis. (Asteraceae), Hieracium laevigatum Willd. (Asteraceae), Laserpitium latifolium L. (Apiaceae), Ortilia secunda (L.) House (Pyrolaceae), Pulsatilla patens (L.) Mill., Ranunculus lingua L., (Ranunculaceae); Scorzonera austriaca Willd. (Asteraceae), Serratula bulgarica Acht. & Stoj. (Asteraceae), Thymus calcareus Klokov et Des.-Schost. (Lamiaceae), Vincetoxicum fuscatum (Hornem.) Reichenb. fil. (V. intermedium Taliev) (Asclepiadaceae), Monotropa hypophegea Wallr. (Monotropaceae); (3, 4, 5) Endangered (EN) – Aconitum lasiostomum Rchb. et Besser (Ranunculaceae), Astragalus pastellianus Pollini (Fabaceae), Carex paniculata L. (Cyperaceae), Linum linearifolium Javorka (Linaceae); Rosa pygmaea Bieb. (Rosaceae), Rosa frutetorum Bess. (Rosaceae); Serratula lycopifolia (Vill.) A. Kerner (Asteraceae); (3, 4, 5) Vulnerabile (VU) – Aconithum eulophum Rchb. (Ranunculaceae), Seseli peucedanifolium Besser (Apiaceae), Scorzonera mollis Bieb. (Asteraceae), Serratula coronata L. (Asteraceae), Alyssum gmelinii Jord. (Brassicaceae); (3, 4, 5) The legal and institutional framework on biodiversity conservation in the Republic of Moldova requires modifications in accordance with the current exigencies, and the legislation must be respected.