Glycosides of polyhydroxysteroids from starfish were compared with regard to hemolytic activities on mouse red blood cells and cytotoxicity on developing eggs of sea urchin Strongylocentrotus intermedius. Mediasteroside M(1) from Mediaster murrayi with a 2-O-methyl group at a xylose residue exerted lower activity than mediasteroside M(2) without this group. Ceramasteroside C(2) from Ceramaster patagonicus having a 2,4-di-O-Me-Xylp residue had more activity in comparison with ceramasteroside C(3) with 2-O-Me-Xylp. Activities of rathbuniosides R(1) (four OH-groups) and R(2) (five OH-groups) from Asterias rathbuni, and culcitosides C(2) (six OH-groups) and C(3) (five OH-groups) from Culcita novaeguineae were inversely proportional to the number of hydroxyl groups of the aglycon. There was a correlation between cytotoxic and hemolytic activities. The results indicated that salt concentration, temperature and pH values are important for the hemolytic activity of steroid glycosides.