The constitution and stereochemistry of 4β-hydroxy-18-norhibaene (1) and the 4α-epimer (2) are assigned on the basis of spectroscopic properties and dehydration products. Oxidation of erythroxylol A (3) with chromic acid gave nine isolable compounds including the two tertiary alcohols (1) and (2) which must arise from the novel oxidative cleavage of the primary alcohol. The epoxides (8), (9), and (10) derivable from (+)-hibaene, erythroxylol A, and erythroxylol A acetate have also been shown to occur naturally.