On separating the combined chloroformic alkaloids of Galanthus caucasicus (Bak.) Grossh. by chromatography on a column of alumina, we obtained from the ethereal eluate a new base (galanthusine) with mp 118-119°C (acetone), [α]~ -66.6° (c 0.42; ethanol), C₁₅H₂₃NO₅, mol. wt. 333 (mass spectrometrically), Rf 0.45 in TLC on Al₂O₃ [butan-l-ol-water-acetic acid (20 : 20 : 1)], and its hydrobromide with mp 198-200°C (with foaming). The IR spectrum had absorption bands at 3400-3200 (OH) and 940 (>CH₂) cm⁻¹; UV spectrum showed λmax (ethanol) 242, 292 nm (log ε 3.87, 3.77). In the NMR spectrum, signals included aromatic protons (2.63, 3.48 ppm, τ scale), -O-CH₂-O- group (4.22 ppm), olefinic proton (4.40 ppm, C-4), OCH₃ (6.44 ppm), and >N-CH₃ (8.42 ppm). The mass spectrum exhibited a molecular ion peak at m/e 333 and fragments (M - H₂O, M - CH₃O, M - CH₃OH, M - H₂O - CH₃OH), with a pattern characteristic of lycorenine-type alkaloids, indicating a hydroxy group at position 5 of the lycorenine skeleton. The M - 32 peak and NMR signal at τ 6.44 ppm suggested an alicyclic methoxy group, which was inferred to be at position 6 (excluding positions 2, 3, 5). Based on these findings, the most probable structure c was proposed for galanthusine.