The alkaloids of Buxus sempervirens L. (common box) cultivated in the USSR were investigated. The alkaloid content in various organs from different growth sites was determined by the chloroform method. From 30 kg of thin flowers and leaves, the benzene-soluble fraction of combined alkaloids was isolated, and a base (I) with the composition C₂₅H₄₂N₂O was obtained. Its structure was analyzed using IR, NMR, and mass spectrometry, and derivatives including N,N',O-triacetate (II), N,N'-dimethyl derivative (III), and dihydro derivative (IV) were prepared for structural confirmation. A mixture of (I) with cyclobuxine D showed no melting point depression, and they had the same Rf value on TLC, indicating (I) is cyclobuxine D.