Lanosterolderivatives with a functional group at C-32 have been synthesized from 3 beta-acetoxylanostan-7 alpha-ol. The key reaction of the synthesis is the hypoiodite reaction of 3 beta-acetoxylanostan-7 alpha-ol. In vitro antitumor activity testing of the lanosterolderivatives revealed that 3 beta-hydroxylanost-7-en-32-oic acid has antineoplastic activity.