Some 80 degraded carotenoids, derived from the terminal part of cyclic carotenoids, have been encountered in tobacco to date. These comprise C9 to C13 compounds, most of which can be viewed as being formed by initial oxidative cleavages of the 7,8 to 10,11 bonds in the carotenoid polyene chain. Although frequently present in low concentrations, many of them are important contributors to the tobacco flavour. In view of this and the crucial role played by mass spectrometry in correlating chemical and sensoric data and obtaining structural information on minute quantities, a study of their mass spectra has been performed, the results of which will be presented.