In immunotherapeutic research, over the last two decades, very intensive investigations were carried out of the preparation, experimental and clinical characteristics of a relatively new category of active substances, the so-called immunostimulants. They are products of natural or synthetic origin with different chemical characteristics and mechanisms of action (1). Such an immunostimulating drug is Sterodin ® . It is the proprietary name of the medicine produced from bile lipids and bacterial metabolites from Staphylococcus albus, Micrococcus catarrhal, E. coli, Paratyphoid A and B, Staphylococcus aureus, etc. Each strain has a definite number of cells in each mL of solution. Sterodin ® has been claimed to possess a non-specific immunopotentiating activity, particularly in infectious diseases. However, the mechanism of action and the exact parameters that are influenced by Sterodin ® are still unknown. Therefore, we performed some toxicological and pharmacological evaluations to get some basic data about Sterodin ® . Sterodin ® is a novel non-specific immunostimulating drug produced by a combination of bile lipids and bacterial metabolites. In the present study, we investigated some of its (i) toxicological and (ii) pharmacological properties in vivo, and (iii) drug-lipid interaction (lipid peroxidation) in vitro. We also evaluated the possible (iv) Sterodin ® -induced lipid peroxidation as well as the effect of ascorbic acid on this peroxidation. We found LD 50 of Sterodin ® to be 31.50 mL kg -1 body mass. In male albino mice, Sterodin ® increased the total white blood cells and neutrophils count by 59 and 26 %, respectively, on the 6 th day, compared to day 0 after injection and stimulated phagocytic activity in vivo. We used goat liver as lipid source in drug-lipid interaction studies in vitro. Our experiments show that Sterodin ® induces lipid peroxidation, which was prevented by ascorbic acid.