Four new Amaryllidaceae alkaloids, named lycoranines C-F (1-4), together with seven known ones (5-11) were isolated from the bulbs of Lycoris radiata. Their structures with absolute configurations were elucidated by nuclear magnetic resonance, high-resolution electrospray ionization mass spectrometry, circular dichroism spectra, modified Mosher's method, and molecular modeling calculation. Compounds 6, 7, 10, and 11 exhibited a potent inhibitory effect on A549 and LoVo cells with IC50 values ranging from 3.97 ± 0.36 to 17.37 ± 1.57 μM. © Georg Thieme Verlag KG Stuttgart New York.