AbstractThe crystal structure of axillarine hydrobromide ethanol solvate has been determined from analysis of photographic X‐ray data. The crystal system is orthorhombic, space group P212121, with unit cell dimensionsa= 9.89,b= 11.23,c= 20.83 Å. The structure was determined by means ofPattersonandFouriersyntheses, and refined by the method of least‐squares to an R index of 9.4%.The structural features of axillarine are noted and compared with those of several other pyrrolizidine alkaloids. The NMR. chemical shift difference between the signals due to the non‐equivalent C(9) protons in alkaloids derived from retronecine is also dis