Résumé : The structures of bicyclovetivenol (I) and tricyclovetivenol (II), two primary alcohols isolated earlier by Ruzicka and Semmler, have been determined using classical chemical methods and infra-red spectroscopy. The determinations are based on the study of the corresponding unsaturated hydrocarbons bicyclovetivene (III) and tricyclovetivene (IV), obtained by pyrolysis of the acetates of the corresponding dihydroalcohols. The structures of the alcohols are, respectively: 6-hydroxymethyl-2-methyl-9-isopropenyl-(0:3:5)-bicyclodecane (I) and 2-hydroxymethyl-9-isopropenyl-3:6-endomethylene-(0:3:5)-bicyclo-decane (II). © 1961.