An analysis of literature material has shown that the stability of the M+ ions of bases with the hetisine skeleton decreases considerably when an OR group is present at C-1, C-6, or C-9. The directions of fragmentation are not monotypical and depend greatly on the positions of the oxygen substituents. A similar conclusion can be made from a study of the group and individual features of the breakdown of hetisine, nominine, talatisine, and their derivatives revealed with the aid of high-resolution mass spectrometry and MD spectra. An unusual property of these spectra is the formation of nitrogen-free fragments. The mass spectra of hetisine alkaloids of a new type - zeraconine and its N-oxide - have been characterized. © 1988 Plenum Publishing Corporation.