New findings of 38 vascular plant species in the upper part of the Lena River basin (mostly, Kazachinsko- Lenskii Region of Irkutsk Oblast’) are presented. Caulinia tenuissima is the new species for Siberian flora, and Ptarmica vulgaris is the new species of the Irkutsk Oblast’s flora and Hieracium tunguscanum is the new speceis for northern part of Irkutsk Oblast’. Two species (Elodea canadensis, Potamogeton×bottnicus) are registered in the upper part of the Lena River basin for the first time. Such species as Cerastium pauciflorum, Elymus pubiflorus, Fragaria orientalis, Hieracium fariniramum, Lycopodium juniperoideum, Thalictrum contortum, are found on Baikalskii Ridge for the first time.