Four new sesquiterpenes: sesquithujene, cis-sesquisabinene hydrate, and 2-methyl-6-(trans-4′-methyl-4′-hydroxycyclohex-2′-enyl)-hept-2-ene (zingiberenol) from Zingiberofficinale and sesquisabinene from Pipernigrum are reported. Similarities in the i.r. and n.m.r. spectra between monoterpenes and their sesquiterpene analogs are used to assist in the structural elucidation.