SCi-B-Vac, the 3rd hepatitis B vaccine , was selected for clinical evaluation on the basis of toxicologic profiles in preclinical studies. These studies were performed to obtain information on its toxic signs, organs which are mainly affected, and to estimate its lethality in mice and rats given Sci-B-Vac through two routes of administratin. In male and female rats given a single intragastrical dose of Sci-B-Vac, we estimated that $LD_{50}$ values were over 2.00 ml/100g B.W. (10ng/ml), respectively.