Protein biosynthesis was stimulated in liver tissue in vivo and in vitro after administration into mice of either phytoecdizone of turkesterone (0.5 mg/100 g) or of anabolic steroid compound nerobole (1 mg/100 g). Stimulation of protein biosynthesis was due to an increase in functional activity of polyribosomes and to elevation in the synthesis of protein molecules. Actinomycin D, which inhibited the stimulation of protein biosynthesis in liver tissue of mice treated with nerobole, did not affect the phenomenon in mice treated with turkesterone.