Cytotoxic activity of dammarane triterpenoids isolated from beach leaves was studied. These substances differ from the native ginseng genin (20(S)-protopanaxadiol) by the number, location, or configuration of OH-groups. Using fertilized egg cells of sea urchin Stronglyocentrotus intermedius we demonstrate that the orientation of C-3 OH-group has no effect on cytotoxic activity of triterpenoids as well as a higher activity of a triterpenoid with 3 alpha,12 beta-OH as compared to a C-3 ketone but lower activity as compared to a triterpenoid with 3 alpha,17 alpha-OH. Depending on the number of OH-groups the cytotoxic activity of triterpenoids decreases in the row: tetraol > pentaol > triol. Dammar-24-ene-3 alpha 2 beta,17 alpha,20(S)-tetraol (compound IV) is cytotoxic for the Ehrlich ascite carcinoma cells and this effect is additive to cytotoxic activity of anthracycline antibiotic carminomycin in vitro. Compound IV changes the permeability and microviscosity of the tumor cell membranes.