In connection with a personal case, 100 chemodectomas of the vagus described in the literature have been collected: revealing themselves in 75p. 100 of the cases in the form of cervical and pharyngeal tumours, 50p. 100 of the tumours of the vagal glomus involve some neurological manifestations mainly in the form of lesion of the lower cranial nerves. These appear to be either affected in isolation (41 p. 100) or in a dissociated manner (59 p. 100). Intra-cranial extension is rare (7 p. 100 of the cases) and delayed. Carotid angiography is characteristic. 76 p 100 are intra-vagal, 24 p. 100 are para-vagal and 60 p. 100 are located in the plexiform ganglion. Multifocal forms which account for 17 p. 100 of the cases are more usually, but not exclusively, familial. Surgical treatment is followed by sequelae or complications in more than half the cases. Close attention has been paid to pathogenetic theories: chemodectomas of the vagus may develop from type I chemoreceptor cells of the carotid glomera or from distinct cells with different properties (S.I.F. cells). They may equally well develop from nonchromaffin paraganglionic cells which have not migrated in the normal manner. The finding of such cells in the nerves of new-born babies and adults supports this theory, at least for some chemodectomas of the vagus.