Three new sterols, 3beta,16alpha-dihydroxy-5alpha,17beta-cholestan-21-carboxylic acid (1), 3beta-acetoxy-16alpha-hydroxy-5alpha,17beta-cholestan-21-carboxylic acid (2) and 3beta-(3-hydroxybutyroxy)-16alpha-hydroxy-5alpha,17beta-cholestan-21-carboxylic acid (3) were isolated from Selaginella tamariscina (Beauv.) Spring (Selaginellaceae). Their structures were elucidated based on NMR analyses. The growth inhibitory effects and differentiation induction abilities of compounds 1 - 3 were determined in human leukemia HL-60 cells. Compound 1 was more effective than compounds 2 and 3 in inhibiting cell growth, but compound 3 was more effective than compounds 1 and 2 in enhancing induction of all- trans-retinoic acid differentiation.