1. The composition of the mono- and sesquiterpenoids of the essential oil ofLedum palustre L. var.vulgare Ledeb. has been studied.
2. It has been established that the composition of the essential oil of a Siberian specimen of crystal tea ledum differs from those of European specimens.
3. The predominating components of the monoterpenoids of the essential oil studied were compounds of the para-menthane series: limonene, p-mentha-1(7)-8-dien-2-ols (I) and (II); and, among the sesquiterpenoids, allo-aromadendrene, palustrol, and ledol.